Hoffman Controls 890-DSQ Series User manual
The Class II 890-DSQ micro controller based universal sequencer
provides a fully programmable platform to sequence multiple
loads using SPDT relay closures. The multiple loads may consist
of condenser fan motors, heating elements, compressors or other
sequencing applications. The 890-DSQ Sequencer's versatility
includes a wide range of input and output options. This universal
sequencer can use 1) up to six (0-5 VDC) temperature sensors or
pressure transducer inputs or 2) a single 0-10 VDC input. The
sequencer also has three 0-10 VDC, EC motor speed control
outputs which can be re-configured as three 10 - 0 VDC motor
speed outputs. There are three, 17.5 volt (80Hz) PWM EC motor
speed control outputs and up to six 24 VAC fixed staged outputs,
with an additional six 24 VAC fixed staged outputs available on
a separate expansion board (total of 12 fixed relay output stages).
Hoffman|Controls
Complete Installation &
Operating Instructions
1
General
entire range. Typically, a mix of PSC and continuously variable
entire range. Typically, a mix of PSC and continuously variable
speed EC powered motors are used with
speed EC powered motors are used with
in the same condenser
in the same condenser
bank
bank
.
.
The advantage of continuously variable airflow is that it that
the head pressure can be more accurately maintained than by only
switching the condenser fan motors on and off.
The 890-DSQ Sequencer's variable stage operates as follows:
When the next fixed speed fan is turned on, the variable speed fans
drop in rpm to compensate for the additional fixed speed fan. As
the sensor input continues to go up, the variable speed fans in-
crease speed until the next fixed speed fan turns on, at which point
the variable speed fans drop in rpm again. This process also works
in reverse as the input decreases. Hysteresis is also provided so that
no short cycling of the fixed speed fans occur.
Set point Values
The 890-Series sequencers can utilize up to two (2) sets of set
point values, a primary set and a secondary set. Each set can utilize
a maximum of 12 stage turn on and turn off values (24 set points).
The primary set of set point values is the set typically used. The
secondary set of set point values can be used, on demand, when-
ever the sequencer's "2ND" input terminal is connected to the
adjacent "GND" terminal thru an external contact closure.
The 890 Control consists of a Kydex covered PCB, on stand
offs, with a 32 character LCD display and five push buttons. The
sequencer can be manually operated by following the LCD's menu
system and selecting the available options, parameters and numer-
ical values, using the 5 push buttons. The LCD display routinely
shows a Home Screen and, when selected, up to 6 mode screens
and a number of additional menu and submenu screens.
The LCD's Home Screen always displays the number of fixed
relay output stages that are turned on, along with the selected
maximum number of stages, and the currently used input's value
(temperature, pressure or 0-10 VDC). When the VS (variable
stage) option is selected, the Home Screen also displays a speed
index (percent) of the continuously variable stage's EC motors
speed or percent of SCRs total output current, along with a
number representing the total of all the relay stages and effective
variable stages that are turned on (see Mode 2.2, page 4.)
Due to the availability of various speed EC motors, the
displayed EC motor speed is shown as a speed index, which is
the percent of full speed (10%, 50%, 76% etc.) that the motor is
operating at. For example: a 1075 rpm variable speed EC motor
showing a speed index of 75 (%) would be running at 806 rpm.
The five push buttons (MODE, UP, DOWN, EXIT and
ENTER) allow the installer to change 1) the number of fixed
stages used, 2) the number of inputs used along with the input
Description
890-DSQ Series Microprocessor
Based Universal Sequencer
The 890-DSQ can be setup as a traditional sequencer or as a true
continuous vernier sequencer, when using continuously variable
EC motors or SCRs as the (VS) variable stage. The sequencer can
be operated locally, using the 5 push buttons and the information
shown on the LCD screen or remotely using a Modbus RTU master
control.
The 890-DSQ Series sequencers require 24 VAC (1 VA) to
power the control.
IMPORTANT: When using the 890-DSQ Sequencer, select
a transformer to meet the requirements of all the 24 VAC compo-
nents being used.
The 890-DSQ Series sequencer is typically used, in an A/C
system, to sequence multiple condenser fan motors, on and off,
to provide low ambient condenser control. The 890 has up to six
temperature or pressure inputs that are used to sequence up to 12
fixed speed condenser fan motors or other loads.
A unique feature is that the 890 also provides three (3) PWM,
or three (3) 0-10 VDC or three (3) 10-0 VDC outputs that are
used to drive continuously variable speed EC fan motors. When
the variable speed fans are present, the sequencer intelligently
modifies the output to the variable speed fans so that, as the addi-
tional fixed speed fans are sequenced on or off, the overall effect is
that the
total fan outputs' airflow varies continuously over the
total fan outputs' airflow varies continuously over the
CAUTION:
Failure to read and understand the accompanying
instructions and diagrams prior to energizing the
890 Sequencer may result in permanent damage to
the sequencer.
Introduction
2
type (temperature, pressure or 0-10 VDC), 3) the selection of
the used fixed stage's individual (primary or secondary) set point
values, 4) the selection of the fixed stage's activation modes [LIFO,
FIFO or Binary Encode] and 5) the three scaling percentages, used
to match the sequencer's PWM and VDC output signal's param-
eters, to the variable stage EC motors' input signal's specifications.
The 890-DSQ Sequencer is available a 6 fixed stage model, with
an additional "variable stage output". The "variable stage output"
consists of the "PWM" and "VDC" outputs and their associated
"GND" terminals. There are three sets of "VDC" outputs and
associated "GND" terminals and three sets of "PWM" (17.5 volt,
80 Hz) outputs and their associated "GND" terminals (12 termi-
nals total).
A total of 3 continuously variable, VDC and/or PWM con-
trolled, EC motors may be wired (in any combination) to the
VDC and/or PWM output terminals. For heating applications, a
maximum of 30 mA is available to operate the SCRs.
The 890-Series sequencer can be used for local, remote or a
combination of both local and remote operation. Remote opera-
tion can be implemented, at any time, by using a Modbus RTU
master computer to send the appropriate register data, listed
in Tables 2A & 2B, on pages 16 & 17, to the 890-DSQ Series
sequencer's internal data registers. The sequencer communicates
via a 3 wire Modbus RTU connection to the Modbus RTU master
computer. All of the 890-DSQ Sequencer's options, parameters
and numerical values can be read and set remotely using the
Modbus RTU connection. During remote operation, the Modbus
master reads and writes to the 890-DSQ Sequencer's 76 internal
data registers, using Modbus RTU commands 3, 6 and 16 (hexa-
decimal 10).
BUTTON LOCKOUT FEATURE: The 890-DSQ
Sequencer is equipped with a push button lockout feature. This
feature is Off (disabled) by default, but can be turned On or Off
using the menu system or remotely using the Modbus connection.
If the lockout feature is enabled and the buttons are locked, the
installer will not be able to operate the sequencer manually using
the push buttons. The LCD screen will display "Locked - Enter
Code" whenever a push button is pressed.
The buttons can be unlocked by simultaneously pressing and
holding down these four push buttons: "MODE, UP, EXIT and
ENTER" until after the word "SUCCESS" appears on the LCD
screen (approximately 2 seconds). The buttons will now operate.
Unlocked buttons can be locked by simultaneously pressing
and holding down the same four push buttons: "MODE, UP,
EXIT and ENTER" only until the words "Locked - Enter Code"
appears on the LCD screen. If the four buttons above are not
released immediately when "Locked - Enter Code" appears, the
word "SUCCESS" will appear on the LCD screen causing the
buttons to remain unlocked.
Pre-Installation Information/
Instruction
When the lockout feature is enabled, unlocked buttons will self-
lock after five (5) minutes of no button activity.
LCD BACKLIGHT FEATURE: The LCD's backlight will
remain on while checking or updating the 890-DSQ Sequencer's
selections using the push buttons. After five (5) minutes of push
button inactivity, the backlight will turn off. Pushing any button
afterwards re-activates the backlight.
RELAY FIXED STAGE TEST FEATURE: The 890-
DSQ Sequencer has a relay fixed stage test feature which allows
the installer to sequentially turn on, then turn off, each stage to
individually verify condenser fan or SCR operation (see Operating
Modes section, MODE 1, on page 4).
INPUT SENSOR VALUE FEATURE: Each of the
sequencer's used input sensor values (temperature in °F or pres-
sure in PSI) can be displayed, on the LCD, by pressing the UP
button when the LCD's screen displays the Home Screen. The
sensor values are shown across the screen from left to right. The
first three (3) sensor values are shown on the LCD screen's top line
[input one (1) on the left side] and the last three (3) sensor values
are shown on the bottom line [input sensor four (4) on the left].
Unused input values are not displayed.
The 890-DSQ Sequencers come with a pre-programmed series
of fixed relay stage set point values (turn on & off). Each one
of the relay's turn on and turn off values may be individually
adjusted, either locally or remotely to suit a particular installation.
When a unique application requires the selection of different set
points, other than the pre-programmed set points, a new set of
set point values can be automatically calculated by the sequencer's
micro controller, using equal spacing between stages. Any or all of
the programmed set point values can be updated, manually.
The selection of EC motors depends upon the end use of the
EC motor. When the EC motors will be used as variable stage
modulating motors, they must be continuously variable EC motors
that accept a 1) 0 - 10 VDC, or 2) 10 - 0 VDC or 3) 17.5 volt,
80 Hz PWM control signal. These continuously variable EC
motors do not need to have the same horsepower and maximum
rpm as the fixed rpm, staged PSC and EC motors. The ratio of
max performance can be set in the controller. However, installing
continuously variable EC motors that have the same size, line
voltage, horsepower and maximum rpm as the fixed rpm, staged
PSC motors, they are replacing, makes the installation simpler.
When the EC motors will be used as staging motors, they
should provide the same performance (size, line voltage, horse-
power, maximum rpm and airflow) as the other staged motors.
When updating a bank of 4 or 6 PSC condenser fan motors to
obtain continuous airflow across the condenser, two of the PSC
motors should be replaced with two continuously variable EC
motors, to supply enough modulating airflow, to achieve continu-
ously smooth air-flow thru the condenser coils over the sequencer's
full operating range.
When installing the 890-DSQ Sequencer in a heating system,
and the continuous vernier capability will be implemented, size the
VS (variable stage's) SCR with twice the KW capacity as a single
fixed staged heater SCR to ensure continuously smooth heating
functionality.
Description Con't
3
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Pre-Installation Information/
Instruction Con't
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The 890 sequencer's operation is organized into two sections:
local and remote, with each section containing the same selectable
modes, menus, submenus, settings and numerical values.
The 890-DSQ Sequencer controls its operation by using the
information stored within its micro controller's 76 internal data
registers. These data registers are numbered from 0 to 75, with
each register's data contents representing a unique sequencer func-
tion or numerical value.
Each 890-DSQ sequencer's micro controller is programmed, at
the factory, with the internal register data needed for that sequenc-
er's anticipated application. However, the pre-programmed data
can be changed, during or after installation, by manually and/or
remotely updating the micro controller's internal register data.
Manually updating the internal register data is accomplished by
viewing and then responding to the LCD screen's information and
appropriately pressing one or more of the sequencer's five push
buttons.
Manual operation starts with the LCD's Home Screen (Figure
1). The Home Screen displays the number of fixed relay stages
turned on, along with the maximum number of selected stages,
(Stages On: 1/4), along with the selected input type (Tm p , PSI or
VDC) and that input's present value (Tmp: 53.1).
When selected, the LCD's Home Screen also displays the variable
stage's percent of operation (VS: 75) along with a number repre-
senting the total of all of the fixed relay stages and effective variable
stages that are turned on (2.5). Refer to Mode 2.2, on pages 4 & 5,
for a description of effective variable stage operation.
The sequencer's MODE button is used to sequentially cycle thru
the LCD screen's six (6) available modes. Pressing the MODE but-
ton once advances the LCD's screen to the "To Test Fans Press
Enter" screen (Mode 1). Slowly pressing the MODE button repeat-
edly, cycles the sequencer thru its six (6) available modes and then
back to the Home Screen.
Remotely updating the 890-DSQ Sequencer's internal register
data requires connecting the sequencer to a Modbus RTU master
computer that can send new register data to, and/or read current
register data from, the 890 micro controller's internal memory.
NOTE: Since the 890-DSQ's operation is controlled by the
data stored within its internal registers, the sequencer provides the
same identical operation whether the register data is changed locally
(manually) or remotely.
In both local and remote operation the 890-DSQ Sequencer can
be setup to select 1) fan testing, 2) traditional or continuous VS
(variable stage) operation 3) the number and type of outputs used,
4) the number and type of inputs used, 5) the primary, and/or
secondary set point values used, 6) the Modbus communication
parameters and 7) 0 - 10 VDC or 10 - 0 VDC output selection.
Local operation uses the control's five push buttons (MODE,
UP, DOWN, EXIT & ENTER) along with the LCD screen's
information to display and select the sequencer's operating modes,
menus, submenus, options and numerical values.
Each mode has several menus, with some menus having a
number of submenus. Each press of the MODE button displays
the next operating mode's title on the LCD screen. Pressing the
ENTER button, while a particular operating mode's screen is
visible on the LCD, displays that mode's first menu. Pressing the
ENTER button again will display the next menu or submenu asso-
ciated with that mode. The installer can update the displayed menu
options and/or submenu options and numerical values by pressing
the UP or DOWN buttons.
Whenever a
menu screen
is displayed, each press of the UP
or DOWN buttons incrementally cycles thru that menu's avail-
able options. The UP button advances the displayed options in a
forward direction while the DOWN button does the reverse.
Whenever a
submenu screen
is displayed, each press of the
UP or DOWN buttons incrementally cycles thru that sub-menu's
available options or numerical values. Pressing the UP button either
1) cycles forward thru the available options or 2) increases the
displayed value. Pressing the DOWN button either 1) cycles back-
ward thru the available options or 2) decreases the displayed value.
Once an option or numerical value has been updated, pressing
the ENTER button, again, will save the new value and move the
control's operation forward to the next submenu, menu or mode
.
Pressing the EXIT button, at any time, causes the control to
return immediately to the Home Screen. However, any options
or value changes that were not saved, by previously pressing the
ENTER button, will be lost.
Local Operation
Operating Methods
Figure 1
LCD Home Screen
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IMPORTANT:
When using replacement EC motors, review the sys-
tem's current protection device's capability to ensure
the protection devices can handle the much larger in-
rush current experienced during EC motor line
voltage power up.
4
MODE 2: Change output stage settings.
The output stage settings can be changed from the pre-
programed stage options, by pressing the ENTER button when
the above screen appears on the LCD. The LCD screen sequence's
through the following 4 menu screens with each press of the
ENTER button:
1) Is Variable Stage Used? No
The (VS) variable stage is used (activated) when continuously
smooth airflow thru a condenser, or continuously variable current
flow thru a heating system, is desired. Implementing the VS option
requires connecting the sequencer's VDC and/or PWM output(s),
to external SCRs, rated at twice the current capacity of the largest
heating coil, or continuously variable speed EC motors. Press the
UP or DOWN button to change the No to a Yes or vice versa.
Then press the ENTER button to save the correct answer and
advance to the LCD screen below.
2) Variable Stage Ratio: 1.0
When the Is Variable Stage Used? above is selected (Yes),
this screen will appear. The variable stage ratio is used to set the
ratio of the total variable stage capacity to that of a single fixed
stage. In order to provide continuously smooth operation when
using hysteresis, the ratio should be greater than 1.
This unique 890-DSQ feature provides PWM and VDC outputs
that are used to drive variable speed EC motor fans or SCRs. When
the variable speed fans or SCRs are present, the sequencer intel-
ligently modifies the output to the variable speed fans or SCRs so
that, as additional fixed speed fans or fixed heaters are sequenced on
and off, the overall effect produces a continuously variable airflow
(or current) over the entire system's range.
Remote operation is accomplished by using a Modbus RTU
master computer to communicate with the 890-DSQ Sequencer
via the Modbus 3 wire connection. (The third wire is a common
ground reference). During remote operation, the Modbus RTU
master computer can read the information stored in 75 of the 890-
DSQ Sequencer's 76 internal registers (Register 72 is a write only
register). Refer to Tables 2A & 2B (pages 16 & 17) for a complete
list of the registers, by number, and the required data range
allowed for each register. The Modbus RTU master computer can
also write information to 65 of the 76 sequencer's internal registers
(Registers 0-57 & 68-75). Registers 58 thru 67 are read only regis-
ters and therefore ignore any data written to them (see Modbus
Operation section on pages 18).
Operating Modes
NOTE:
The Modbus RTU master control can only write data
to 27 of the 890-DSQ Sequencer's registers at a time,
and read data from 29 registers at a time, due to buffer
size limitations in the sequencer's microcontroller.
IMPORTANT:
If any of the down loaded Modbus data is incor-
rect, the 890-DSQ Sequencer's microcontroller
will change the incorrect data into software
selected default values during the sequencer's next
operating cycle. Therefore, after updating any
data remotely, the operator MUST allow the 890-
DSQ Sequencer to operate over its entire expected
range (°F, PSI or VDC) before reviewing ALL of
the data contained in each of the sequencer's 76
register addresses to 1) ensure that all of the oper-
ating parameters and numerical values, needed
for the application, have been correctly selected
and 2) also ensure that any unneeded or undesired
options or numerical values have not inadvertently
been left selected.
The following information is provided to identify and explain
the 890-DSQ Sequencer's operational modes, menus, submenus,
and numerical value options. The sequencer's MODE button
is used to sequentially cycle thru the seven (7) available modes
displayed on the sequencer's LCD screen. Pressing the MODE
button an eighth time returns the LCD to the Home Screen.
An 890-DSQ Operating Modes Chart (Figure 3, pages 10 &
11) is provided to allow the operator to track his/her progress thru
the various LCD's screens. The Operating Modes Chart's informa-
tion is viewed starting from the Home Screen, located at the top
center of the Operating Modes Chart, and continuing counter
clockwise (to the left) around the chart.
NOTE: The Figure 3, 890-DSQ Operating Modes Chart, (on
pages 10 & 11) information is presented in the same mode, menu
and submenu order as the information presented on the LCD
screen, when following the chart's information in a counter clock-
wise direction (to the left). Press the MODE button to begin.
MODE 1: To Test Fans Press Enter.
The contactor wiring and condenser fan or heating element
wiring, connected to each relay output, can be sequentially
tested in this mode, by pressing the UP and DOWN buttons.
Pressing the UP button turns on the next stage, while pressing
the DOWN button turns off the last stage, that is currently on.
Operating Methods Con't
REMOTE OPERATION
IMPORTANT:
After updating any information displayed on the
LCD's screen, the installer MUST review ALL of
the 890-DSQ Sequencer's mode, menu, submenu
and numerical value options to 1) ensure that all
of the operating parameters, needed for the appli-
cation, have been correctly selected and 2) also
ensure that any unneeded or undesired options or
numerical values have not inadvertently been left
selected.
A traditional sequencer's operation is shown, as a reference, at
the top of Figure 2 (above). The 890-DSQ Sequencer's variable
stage operation is depicted, on it's own, in the center of Figure 2,
while the total sequencer's operation which produces a continuous
output, is shown at the bottom of Figure 2.
When the sequencer's fixed stages are activating, the variable
speed EC motor (or SCR) ramps from a low rpm (or current) to
full speed (or full current) before the next sequencer's fixed stage
turns on. As the next fixed stage turns on, the variable stage's
output immediately drops down the equivalent of one fixed stage.
During stage deactivation, when the previous fixed stage turns off,
the variable stage's output jumps up equivalent to one fixed stage.
As the input continues to decrease, the variable stage's output
ramps down equivalent to one fixed stage just before the, now
current, fixed stage turns off. This combination of fixed stage and
variable stage operation produces a continuously variable (fan rpm
or SCR current) output.
Without hysteresis, the variable stage's airflow capacity or SCR's
KW capacity would only need to be a little larger than a fixed A/C
stage's airflow or a fixed heater element's capacity, due to the elec-
tronic components variances in each fixed stage's turn and turn off
tolerances.
With hysteresis, the EC motor's airflow capacity, or SCR's KW
capacity, needs to be much larger than a single fixed stage's on and
off values. The extra capacity provides enough EC motor speed, or
SCR current variation, to allow continuous increases or decreases
in airflow without short cycling the fixed stages.
When the variable stage ratio is more than 1.0, the 890's micro-
controller uses the variable stage ratio's number as the number of
effective stages to be added to the number of fixed stages selected.
All of these effective stages are activated before the first fixed stage
turns on. The total number of activated, effective and fixed stages
is shown in the LCD Home screen's upper right corner.
A mathematical formula can be used to calculate the size of
the variable stage's ratio number needed for smooth continuous
operation. This ratio number represents the comparison of the
VS (variable stage's) capacity (airflow or KW), to the fixed stage's
airflow or KW capacity. Typical ratios are 1.5 to 2.0 for 4 to 6
stage applications, respectively.
The installer may use the following formula to calculate the
minimum size of the VS (variable stage) ratio:
Variable Stage Ratio = [1+ (the hysteresis value by the
difference between stage turn on values)]
Examples:
1) When the hysteresis is 6 °F and the difference between
stage turn on values is also 6 °F, then the
Variable Stage Ratio =[1+(6 °F hysteresis 6 °F )] = 2.0
2) When the hysteresis is 4 °F and the difference between
stage turn on values is 8 °F, then the
Variable Stage Ratio =[1+(4 °F hysteresis 8 °F)] = 1.5
Use the UP and DOWN buttons to change the VS (variable
stage) ratio's number to match the ratio of the total VS (variable
stage) capacity to that of a single fixed stage. (The range is 1.0
to 12.0). Then press the ENTER button to store this value and
continue to the menu below.
3) Number of used output stages: 6
Use the UP and DOWN buttons to select the number
of relay output stages to be used. The range is 0 to 12
stages. When "0" is selected, only the VS (variable stage's)
EC motors or SCR operation is activated (None of the
fixed relay output stages are used when "0" is selected).
Press the ENTER button when the answer is correct.
NOTE:
For practical reasons, a VS (variable stage) ratio of 2.0 works
well for A/C condenser banks, containing 4 to 6 fan motors,
or heating systems containing 4 to 6 fixed heating
elements.
5
Mathematical Formula
Operating Modes Con't
Figure 2
Traditional Vs Variable Stage Operation
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4) Stage On Delay in seconds: 2
Use the UP and DOWN buttons to change the delay after
a previous relay stage turns on, until the next relay stage can
turn on. The range is 0.0 to 10.0 seconds. (Entering 0.0 acti-
vates the relay stages as quickly as possible).
MODE 3: Change Input Settings.
In this mode, the number of input stages used, the sensor
combination rule used (see MODE 3.2, below) and the
Emergency On value can be changed/updated, from the pre-
programmed value, by pressing the ENTER button when the
above screen appears on the LCD's screens.
The LCD sequences thru the following 3 menu screens with
each press of the ENTER button:
1) Number of Inputs Used: 1
There are three types of input options available on the 890-
DSQ Sequencer; temperature sensors, pressure transducers and
the 0-10 VDC input. Use the UP and DOWN buttons to set
the number of inputs used. (The range is 0 to 6).
When the number of inputs used is set to "0", the 0-10
VDC input is used instead of the six 0-5 VDC temperature
sensors or pressure transducer inputs. NOTE: The six tem-
perature sensors and six pressure transducer inputs are ignored
when the number of inputs is set to "0".
Press the ENTER button to store the value selected, for the
number of inputs used, and proceed to the submenu below.
2) Input Combination Rule: Maximum
This screen is only displayed when more then a single
temperature sensor or pressure transducer input is used. The
installer must choose 1 of 4 possible ways to combine the
temperature sensors or pressure transducer's input values.
The four choices are; Maximum, Second Highest, Average or
Median.
The Maximum option is chosen when only the sensor or
transducer with the highest input value will be used to control
the sequencer's operation.
The Second Highest option is chosen when only the sec-
ond highest sensor or transducer input value will be used to
control the sequencer's operation.
The Average option is chosen when the numerical average
of all used sensor or all used transducer input values will be
used to control the sequencer's operation.
The Median option is chosen when the middle value of all
used sensors or all used transducer input values will be used to
control the sequencer's operation.
Use the UP and DOWN buttons to sequentially display
(cycle thru) each of the four combination rules. Then press the
ENTER button, when the desired rule is visible on the LCD
screen, to store that combination rule and continue to the next
menu.
3) Emergency On Temp/Pres: 95.0
This screen appears when temperature sensor or pressure
transducer inputs are selected. If any of the used temperature
sensor or pressure transducer input values reach or exceed the
selected Emergency On value (max 115 °F or 1000 PSI), all
of the remaining inactivated relay stages will turn on sequen-
tially. Use the UP and DOWN buttons to select the desired
Emergency On temperature, then press the ENTER button to
store the value and continue to the next mode below.
MODE 4: Change Primary Set Points
The primary set point values can be changed/updated, from the
pre-programmed set point values, by pressing the ENTER button
when the above screen appears on the LCD screen.
When the number of fixed output stages is selected, the 890-
DSQ Sequencer loads a pre-programmed set of turn-on and
turn-off set points into the microcontroller's memory. The installer
can use the pre-programmed set points or modify any or all of
these set points as required by the application.
To change all of the set point values automatically, see MODE
4.1 below. To manually update any or all of the set point values
individually, see MODE 4.2 on page 7.
The stage's turn on and turn off values are associated with one
of the 3 input types; temperature, pressure or 0-10 VDC. The
set point values are in °F when the inputs used are temperature
sensors, PSI when the inputs used are pressure transducers or volts
DC when the 0-10 VDC input is used.
The LCD sequences thru the following 3 menu screens with
each press of the ENTER button:
1) Set Stage On/Off
Values Auto? 1
This menu is used to automatically set all of the used stages'
primary on and off values by uniformly distributing the stage's
operation over a selectable span. The selectable span's low and high
values are set in the first two submenus below. The third submenu
displays the calculated stage turn on spacing and resulting stages'
hysteresis. The number "1", in this menu's LCD screen, indicates
the primary set points can be changed at this time. Press the
ENTER button to start the automatic selection process.
OR
To independently set each stages' on and off values manually,
press the UP or DOWN button ONCE and then press the ENTER
button to advance the LCD's screen to MODE 4.2, Set Stage On/
Off Values Manual 1 (on page 7).
a. Low Span Value
Temp/PSI/Volts: 50.0
Use the UP and DOWN buttons to change the low span's value
(number) to match the lowest input value at which the unit will
come on. If the VS (variable stage) has not been selected, this is
the value at which stage 1 turns on. If the VS (variable stage) has
been selected, this is the value at which the variable speed EC
motors begin to increase speed from 0 rpm, or the SCR begins
supplying current to the heater.
Press the ENTER button to store the low span's value and
continue to submenu b(on page 7).
6
Operating Modes Con't
7
b. High Span Value
Temp/PSI/Volts: 80.0
Use the UP and DOWN buttons to change the high span's
value (number) to match the highest input value at which the
unit has all the fixed relay stages on, plus the VS (variable stage)
at 100% (if the VS is being used).
Press the ENTER button to store the high span's value and
continue to submenu c. below.
c. On to On=2.0 Deg/PSI/Volts
Hyster= 1.0 Deg/PSI/Volts
This submenu displays the stage spacing between successive
relay turn on values. This submenu also shows the current hys-
teresis value used for each of the activated relay stages.
The first line on the LCD's screen shows the evenly spaced
temperature, pressure or voltage differences between successive
fixed stage turn on values, calculated by the microcontroller,
using the high and low span values entered above.
The second line on the LCD's screen shows the current hys-
teresis value (in °F, PSI or volts DC) used for all the selected
relay stages. The operator may change this hysteresis value by
pressing the UP or DOWN buttons until the desired hysteresis
value, used by all the selected (fixed) relay stages, is displayed on
the LCD screen's second line. However, the selectable hysteresis
values are limited due to the span size chosen in MODES 4.1a
and 4.1b above.
NOTE: Hysteresis is used to prevent short cycling. It is the
difference between each stage's turn on and turn off values. Press
the ENTER button to save the hysteresis value and continue to
menu 2 below.
2) Set Stage On/Off
Values Manual 1
To set any or all of the primary set points (stage turn on
and turn off) values manually, press the ENTER button.
a. Var Stage TurnOn
Temp/PSI/Volts: 50.0
If VS (variable stage) operation is selected, this screen will
appear. Use the UP and DOWN buttons to set the value at
which the continuously variable EC motors, or SCRs, first
begin to turn on. Press the ENTER button to save the value
and continue to submenu b below.
b. Stage 1 On Temp/PSI/Volts
61.5?
Use the UP and DOWN buttons to set the value at which
relay stage 1 turns on as the input rises. If the variable stage is
being used, this value must be above the value at which the
variable stage turns on. Otherwise the stage's turn on value
will default to 0.2 (°F, PSI or VDC) above the variable stage
turn on value. Press the ENTER button to continue.
IMPORTANT:
After updating any information displayed on the
LCD's screen, the installer MUST review ALL of
the 890-DSQ Sequencer's mode, menu, submenu
and numerical value options to 1) ensure that all
of the operating parameters, needed for the appli-
cation, have been correctly selected and 2) also
ensure that any unneeded or undesired options or
numerical values have not inadvertently been left
selected.
c. Stage 1 Off Temp/PSI/Volts
56.0?
Use the UP and DOWN buttons to set the value at which
Stage 1 turns off as the input drops. This value must be below
the value at which Stage 1 turns on. Otherwise, the stage 1
turn off value will default to 0.1 (°F, PSI or VDC) below the
Stage 1 turn on value. Press the ENTER button to continue.
d. Stage 2 On Temp/PSI/Volts
67.0?
Use the UP and DOWN buttons to set the value at which
Stage 2 turns on as the input rises. This must be above the
value at which Stage 1 turns on. Otherwise the Stage 2 turn on
value will default to 0.2 (°F, PSI or VDC) above the Stage 1
turn on value. Press the ENTER button to continue.
e.Stage 2 Off Temp/PSI/Volts
61.5`?
Use the UP and DOWN buttons to set the value at which
Stage 2 turns off as the input falls. This must be below the
value at which Stage 2 turns on. Otherwise the Stage 2 turn off
value will default to 0.1 (°F, PSI or VDC) below the Stage 2
turn on value. Press the ENTER button to continue.
Continue to manually set the individual relay stage's on and off
values, as described above, until the number of used output stages'
primary set points have been set.
MODE 5: Change Secondary Set Points
The 890-DSQ Series sequencers include a second set of set
points that can be stored and used when an application determined
condition occurs. The sequencer will operate using the secondary
set points when an external contact is closed, connecting the input
terminal labeled "2ND" to the adjacent "GND" terminal. Press
the ENTER button to begin setting the secondary set points.
The LCD screen will show "Set Stage On/Off Values Auto? 2".
The "2" indicates the 2nd (secondary) set of set point values can
be changed when this menu is selected. The options available to
select these secondary set point values are identical to the options
used to set the primary set point values in MODE 4 above.
Therefore, follow the MODE 4 instructions, when the number
"2" is present on the LCD screen's menu or submenu text, to
update the secondary set points using either Auto or Manual
methods.
Operating Modes Con't
8
stop bits. Then press the ENTER button to save the selected
parity and continue.
5) Change Sensor
Type: Temperature
Use the UP and DOWN buttons to change the input sensor
type. (Choices are temperature or pressure). When the sensor
type is changed from temperature to pressure, or vice versa, the
Emergency On value is reset to either the temperature based
Emergency On value or the selected maximum pressure value.
Press the ENTER button to save the selected sensor type and
continue. If "pressure" is selected, then another menu appears,
requesting the maximum pressure rating of the transducer(s)
used. Select the appropriate value from 100 PSI to 1000 PSI.
6) Relay Sequence
Mode: FILO
Use the UP and DOWN buttons to change the order in
which the relay stages turn on and off. (Choices are FILO,
FIFO and Binary Encode).
FILO mode means the last relay stage to turn on will be the
first relay stage to turn off.
FIFO mode means the first stage to turn on will be the first
stage to turn off. FIFO mode promotes even load operation
(wear) by using each stage an equal amount of time, on aver-
age, by turning on whatever stage has been off the longest and
turning off whatever stage has been on the longest.
Binary Encode
mode uses the Base 2 number counting
system. Binary encode mode is used when the sequenced loads
are a ranged in a 1, 2, 4 weighted ratio (Each load has twice
the capacity of the previous load). This allows the sequencer to
operate 7 stepped loads using only 3 relay output stages (or up
to 12 sequencer loads using 4 relay stages).
Press the ENTER button to save the selected relay sequence
and continue.
7) VarFan SpdLimits OutputHigh: 95
Scales the sequencer's PWM and VDC output signals to
match the selected VS (variable stage) EC motor's full speed
control signal's percentage. For example:
If the VS EC motor goes to full speed as the input signal
rises to 92% PWM or 9.2 VDC, then the VarFan SpdLimits
OutputHigh: number should be set at 92.
NOTE: The LCD's Home Screen will show "VS: 100" indicat-
ing the EC motor is running at 100% full speed. However, the
PWM and VDC output signals will remain set at 92% PWM
and 9.2 VDC as the sequencer's selected input signal continues
to rise.
8) VarFan SpdLimits OutputLow: 20
Scales the sequencer's PWM and VDC output signals to
match the selected VS (variable stage) EC motor's minimum
(low) speed control signal's percentage.
For example:
If the VS EC motor goes to minimum speed as the motor's
input signal drops to 15% PWM or 1.5 VDC, then the
VarFan SpdLimits OutputLow: number should be set at 15.
MODE 6: Special Settings:
MODBUS, I&O, RESET
This mode has 10 menus and is used to set the following options:
•Lockout code activation.
•Modbus slave's address, baud rate and parity.
•Input sensor type (temperature or pressure).
•Relay stage's sequence mode (FIFO, FILO or Binary
Encode).
• Scale the sequencer's variable stage PWM and VDC output
to match the variable stage's, continuously variable speed, EC
motors' full speed, minimum speed and off percentages
• 10 - 0 VDC output selection (by inverting the PWM and 0-
10 VDC output signals).
•Reset the sequencer to factory settings.
The LCD screen sequences thru the following menu and
submenu screens, with each press of the ENTER button. Press the
ENTER button to continue.
1) Lockout Code Enabled?
No
Use the UP or DOWN button to enable (activate) or
disable (de-activate) the Lockout Code. The options are:
"Yes" or "No". Then press the ENTER button to con-
tinue,
2) MODBUS Address: 1
Use the UP and DOWN buttons to set a unique
Modbus slave address for this particular 890-DSQ
Sequencer. (Range is 1 to 247). Then press the ENTER
button to continue.
3) MODBUS Baud Rate
19200
Use the UP and DOWN buttons to select the Modbus
baud rate. The choices are 1200, 2400, 4800, 9600, 19200,
38400, 57600 and 115200. When remotely setting the baud
rate value, a number code, from 0 to 7, is used. Refer to
TABLE 1, Baud Rate Codes below, to view the available 890-
DSQ Sequencer's baud rates and their associated number codes.
The default baud rate is 19200. Press the ENTER button after
making your selection.
Code Baud Rate Code Baud Rate
0 1200 4 19200
1 2400 5 38400
2 4800 6 57600
3 9600 7 115200
Baud Rate Codes
TABLE 1
4) MODBUS Parity
Even Parity
Use the UP and DOWN buttons to set the Modbus parity.
The choices are even parity, odd parity and no parity with 2
Operating Modes Con't
9
NOTE: The LCD's Home Screen will show "VS: 0" indicat-
ing the EC motor is at lowest speed. However, the PWM
and VDC output signals will remain set at 15% PWM and
1.5 VDC, until the VarFan SpdLimits OutputOff: value is
reached (see menu 9 below).
9) VarFan SpdLimits OutputOff: 0
Scales the sequencer's PWM and VDC output signals to
match the selected VS (variable stage) EC motor's off percent-
age. When the sequencer's input temperature sensor (or pres-
sure transducer) value drops below the EC motor's turn on
value (set in MODE 4.1a or 4.2a), the PWM and VDC out-
put signals will linearly decrease from the VarFan SpdLimits
OutputLow: value, to the VarFan SpdLimits OutputOff:
value, over a 2 °F (or 2 PSI) span, to keep the EC motors from
short cycling.
As the input sensor's value continues to decrease, the PWM
and VDC output signal's percentage will remain set at the
VarFan SpdLimits OutputOff: value.
For example:
1) When the sequencer's VS (variable stage's) output signals
are required to decrease to 0% PWM or 0 VDC to turn off the
fan, the VarFan SpdLimits OutputOff: value must be set to
"0".
2) When the sequencer's VS (variable stage's) output signals
are required to decrease to 5% of their full capability, and
remain at 5%, as the input signal continues to decrease, the
VarFan SpdLimits OutputOff: value should be set to "5".
NOTE: The LCD's Home Screen will continue to show "VS: 0",
indicating the EC motor is still off. However, the PWM and
VDC output signals will remain at the PWM and VDC per-
centages set by the VarFan SpdLimits OutputOff: value.
When the variable stage EC motors require a 10-0 VDC
control signal, the VDC output's 0-10 VDC signal can be
inverted (changed to a 10-0 VDC signal) by doing the follow-
ing: (This will also invert the PWM duty cycle)
1) Set the "VarFan SpdLimits OutputHigh:" value to a low
number (usually between 0 and 15).
2) Set the "VarFan SpdLimits OutputLow:" value to a high
number (usually between 80 and 90).
3) Set the "VarFan SpdLimits OutputOff:" value to the
highest number (usually between 95 and 100).
For Example:
To set the EC motor's control signal for full speed at 0 VDC,
minimum speed at 7.7 VDC and off at 9.5 VDC, use:
VarFan SpdLimits OutputHigh: 0
VarFan SpdLimits OutputLow: 77
VarFan SpdLimits OutputOff: 95
Using motors with a 10-0 VDC input control signal pro-
vides a level of safety. If the EC motors using a 10-0 VDC
input signal loose their control signal they will run at full
speed.
10) Reset Control To Factory Settings?
No
Use the UP and DOWN buttons to change the No to a Yes,
or vice versa. Then press the ENTER button when the answer
is correct.
This completes the Operating Modes section.
The 890-DSQ Sequencer's factory default settings are:
Test fans on = 0 (none).
Is variable stage used? No.
Number of fixed stages used = 4 relay output stages.
Stage on delay = 2 seconds.
Number of input stages used = 2 input stage.
Input combine rule = maximum.
Emergency on = 95 °F, 950 PSI or 9.5 VDC.
Change primary set points = No.
Change secondary set points = No.
Lockout enabled? No.
Modbus slave address = 1.
Modbus BAUD rate = Code 4 (19200).
Modbus parity = Even Parity.
Sensor type = Temperature.
Relay sequence = FILO.
Reset control to factory sets? No.
Factory Default Settings
10-0 VDC Output Selection
Installation
IMPORTANT:
Do not install the sequencer in an airtight compart-
ment, on a vibrating surface or near/on heat
generating sources.
IMPORTANT:
The 890-DSQ Sequencer's relay output stages are
only designed for low voltage (24 VAC) operation.
Operating the relay output stages at higher voltages
may result in permanent damage to the sequencer.
Operating Modes Con't
10
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11
The 890-DSQ Series Sequencers may be installed using a range of inputs, staged relay
outputs, and continuously variable speed EC motors or SCR outputs. Refer to Figures 5
thru 8, (pages 12 thru 15), for the appropriate wiring diagram(s) for this application. More
than one wiring diagram's information may be required when installing the 1) Modbus
connection, 2) secondary set point contact closure, 3) 0 - 10 VDC input or 4) VS (variable
stage) EC motors or SCRs.
1)
Wiring must comply with local and national electrical codes.
2)
Disconnect all factory wiring connecting the load (motors, SCRs etc.) to the line.
3)
Refer to Figure 4, Location of 890-DSQ Sequencer's Variable Stage Output,
(below), for the location of the sequencer's variable stage's PWM and VDC output
terminals.
4)
Refer to Figure 5, 890-DSQ Wiring Diagram 1, (on page 12) for applications
using staged relay outputs with temperature sensor inputs. Also see Figure 6, Liquid
Line Temperature Sensor Mounting (on page 13 ) for liquid line temperature sensor
mounting.
a. Mount temperature sensor on top of the liquid line where the line exits the condenser
coil.
Installation Con't
WARNING:
Disconnect power from the condenser fan motors
and heating system to ensure the motors and
heater elements are electrically disabled prior to
installation.
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MODEL 890-DSQ DIGITAL SEQUENCER
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Figure 6
Liquid Line Temperature Sensor Mounting
b.Fasten sensor firmly, only using tape provided. Make sure
the metal tab “heat sink” on the sensor makes firm contact
with the liquid line tubing. NOTE: Using hose clamps or tie
wraps to secure the sensor's metal tab to the liquid line will
break the sensor's internal resistor. Use only the provided
waterproof tape to secure the sensor to the liquid line.
5) Refer to Figure 7, 890-DSQ Wiring Diagram 2, (on
page 14)
for applications using staged relay outputs with pres-
sure transducer inputs.
6) Refer to Figure 8, 890-DSQ Wiring Diagram 3, (on
page 15)
for applications using Modbus, secondary set points,
the 0-10 VDC input, and/or variable stage (VS) EC motors and
SCRs.
7) When using variable speed EC motors, within a bank of 6
PSC condenser fan motors, the least time consuming way to
replace two of the PSC motors, is with 2 variable speed EC
motors, that have the same horsepower, line voltage, frame
size and airflow as the replaced PSC motors.
8) When using SCRs to continuously modulate the current
in a heating system, insert an SCR with twice the current
capability that the heating element to be modulated has.
9) Install and wire the variable speed EC motors or SCRs per
the manufacturers's instructions.
10) Wire the 890-DSQ Sequencer per the wiring diagrams
appropriate for this installation. More then one wiring dia-
gram's information may be used, depending upon the applica-
tion.
NOTE:
Temperature sensors and pressure transducers
can not be used together, as inputs, on the same sequencer.
11) The 890-DSQ Sequencer is designed for low voltage (24
VAC) operation, including the 24 VAC relay stage output
loads.
12) When additional cable is required —
a. Always use 22AWG (minimum) stranded, twisted pair cable
properly insulated for outdoor applications.
b. Sensor or transducer cables, 0–10 VDC input wires,
Modbus wires, and VDC / PWM output wires should not
run in proximity, or be attached, to conduit carrying line
voltage power wires.
13) This completes the 890-DSQ Sequencer's installation.
Initial Sequencer Checkout
• Verify all wire connections are complete and correct for this appli-
cation.
• Apply 24 VAC power to the 890-DSQ Sequencer.
• Perform all Built-In Self Test instructions (below).
The Built-In Self Test function can only be operated in manual
mode, and only simulates the value of a temperature sensor or
pressure transducer or a voltage depending on the input mode cur-
rently selected. The Built-In Self Test allows the installer to use the
sequencer's UP and DOWN buttons to simulate the input value.
For the rest of this section, the simulated input will be assumed
to be temperature.
To begin, press and hold the UP and EXIT buttons down simul-
taneously for about one (1) second. While continuing to hold both
buttons down, press the ENTER button and then release all three
buttons at once. The 890's LCD will display what appears to be
the Home Screen (Figure 1, page 3) and the relays stages may start
turning on, depending on the sequencer's selected set point values.
However, the installer can now change the simulated temperature
shown on the LCD screen's bottom line. Each press of an UP or
DOWN button will raise or lower the LCD temperature by 1.0 °F
The 890-DSQ's operation can be verified by observing each fixed
stage's turn on and turn off temperature, displayed on the LCD's
screen and indicated by each stage's LED. When selected, the VS
(variable stage's) operation can also be verified.
When using the Built-In Self Test function:
1) Verify the fixed relay stages turn on and off at the correct
temperatures, for the application, by observing the LCD
screen's displayed temperature along with each stage's
indicator LED.
2) If selected, verify the 2nd set of set points work cor-
rectly.
3) If selected, verify the VS (variable stage) EC motors (or
SCRs) turn on and reach full speed (or full current) at
the correct temperatures.
4) To exit the Built-in-Self Test function, press the MODE
button and then the EXIT button.
Built-In Self Test
14
MODEL 890-DSQ DIGITAL SEQUENCER
MODEL 890-DSQ DIGITAL SEQUENCER
MODE
MODE
ENTER
ENTER
EXIT
EXIT
UP
UP
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MODEL 890-DSQ DIGITAL SEQUENCER
MODEL 890-DSQ DIGITAL SEQUENCER
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MODE
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EXIT
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DOWN
DOWN
Hoffman Controls
Hoffman Controls
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16
REGISTER
NUMBER MODBUS 16 BIT REGISTER FUNCTION
REGISTER
TYPE
0VS EC motor or SCR Turn-On Temp (°F), PSI or Volts DC (All values times 10) Read & Write
1Stage 1, Primary set point's On Temp (°F), PSI or Volts DC. (All values times 10) Read & Write
2Stage 2, Primary set point's On Temp (°F), PSI or Volts DC. (All values times 10) Read & Write
3Stage 3, Primary set point's On Temp (°F), PSI or Volts DC. (All values times 10) Read & Write
4Stage 4, Primary set point's On Temp (°F), PSI or Volts DC. (All values times 10) Read & Write
5Stage 5, Primary set point's On Temp (°F), PSI or Volts DC. (All values times 10) Read & Write
6Stage 6, Primary set point's On Temp (°F), PSI or Volts DC. (All values times 10) Read & Write
7Stage 7, Primary set point's On Temp (°F), PSI or Volts DC. (All values times 10) Read & Write
8Stage 8, Primary set point's On Temp (°F), PSI or Volts DC. (All values times 10) Read & Write
9Stage 9, Primary set point's On Temp (°F), PSI or Volts DC. (All values times 10) Read & Write
10 Stage 10, Primary set point's On Temp (°F), PSI or Volts DC.(All values times 10) Read & Write
11 Stage 11, Primary set point's On Temp (°F), PSI or Volts DC.(All values times 10) Read & Write
12 Stage 12, Primary set point's On Temp (°F), PSI or Volts DC.(All values times 10) Read & Write
13 Stage 1, Primary set point's Off Temp (°F), PSI or Volts DC.(All values times 10) Read & Write
14 Stage 2, Primary set point's Off Temp (°F), PSI or Volts DC.(All values times 10) Read & Write
15 Stage 3, Primary set point's Off Temp (°F), PSI or Volts DC.(All values times 10) Read & Write
16 Stage 4, Primary set point's Off Temp (°F), PSI or Volts DC.(All values times 10) Read & Write
17 Stage 5, Primary set point's Off Temp (°F), PSI or Volts DC.(All values times 10) Read & Write
18 Stage 6, Primary set point's Off Temp (°F), PSI or Volts DC.(All values times 10) Read & Write
19 Stage 7, Primary set point's Off Temp (°F), PSI or Volts DC.(All values times 10) Read & Write
20 Stage 8, Primary set point's Off Temp (°F), PSI or Volts DC.(All values times 10) Read & Write
21 Stage 9, Primary set point's Off Temp (°F), PSI or Volts DC.(All values times 10) Read & Write
22 Stage 10, Primary set point's Off Temp (°F), PSI or Volts DC.(All values times 10) Read & Write
23 Stage 11, Primary set point's Off Temp °F), PSI or Volts DC.(All values times 10) Read & Write
24 Stage 12, Primary set point's Off Temp (°F), PSI or Volts DC.(All values times 10) Read & Write
25 Emergency On Temp (°F) or PSI (Both values times 10) Read & Write
26 Variable Stage Ratio (Variable Stage Flow Fixed Stage Flow) Read & Write
27 Number of Fixed Stages Used Read & Write
28 Number of 0-5 VDC Inputs Used (Temperature (°F) or Pressure (PSI) Read & Write
29 Input Combination Rule: 1=Maximum, 2=Second Highest, 3=Average, 4=Median Read & Write
30 Use Lockout Code (0= No, 1= Yes) Read & Write
31 Secondary set point's EC motor or SCR Turn-On Temp (°F), PSI or Volts DC. (values times 10) Read & Write
32 Stage 1, Secondary set point's On Temp (°F), PSI or Volts DC (All values times 10) Read & Write
33 Stage 2, Secondary set point's On Temp (°F), PSI or Volts DC (All values times 10) Read & Write
34 Stage 3, Secondary set point's On Temp (°F), PSI or Volts DC (All values times 10) Read & Write
35 Stage 4, Secondary set point's On Temp (°F), PSI or Volts DC (All values times 10) Read & Write
36 Stage 5, Secondary set point's On Temp (°F), PSI or Volts DC (All values times 10) Read & Write
37 Stage 6, Secondary set point's On Temp (°F), PSI or Volts DC (All values times 10) Read & Write
38 Stage 7, Secondary set point's On Temp (°F), PSI or Volts DC (All values times 10) Read & Write
39 Stage 8, Secondary set point's On Temp (°F), PSI or Volts DC (All values times 10) Read & Write
40 Stage 9, Secondary set point's On Temp (°F), PSI or Volts DC (All values times 10) Read & Write
890-DSQ Sequencer's MODBUS Registers' Numbers
TABLE 2A
17
REGISTER
NUMBER MODBUS 16 BIT REGISTER FUNCTION REGISTER
TYPE
41 Stage 10, Primary set point's On Temp (°F), PSI or Volts DC (All values times 10) Read & Write
42 Stage 11, Primary set point's On Temp (°F), PSI or Volts DC (All values times 10) Read & Write
43 Stage 12, Primary set point's On Temp (°F), PSI or Volts DC (All values times 10) Read & Write
44 Stage 1, Primary set point's Off Temp (°F), PSI or Volts DC (All values times 10) Read & Write
45 Stage 2, Primary set point's Off Temp °F), PSI or Volts DC (All values times 10) Read & Write
46 Stage 3, Primary set point's Off Temp (°F), PSI or Volts DC (All values times 10) Read & Write
47 Stage 4, Primary set point's Off Temp (°F), PSI or Volts DC (All values times 10) Read & Write
48 Stage 5, Primary set point's Off Temp (°F), PSI or Volts DC (All values times 10) Read & Write
49 Stage 6, Primary set point's Off Temp (°F), PSI or Volts DC (All values times 10) Read & Write
50 Stage 7, Primary set point's Off Temp (°F), PSI or Volts DC (All values times 10) Read & Write
51 Stage 8, Primary set point's Off Temp (°F), PSI or Volts DC (All values times 10) Read & Write
52 Stage 9, Primary set point's Off Temp (°F), PSI or Volts DC (All values times 10) Read & Write
53 Stage 10, Primary set point's Off Temp (°F), PSI or Volts DC (All values times 10) Read & Write
54 Stage 11, Primary set point's Off Temp (°F), PSI or Volts DC (All values times 10) Read & Write
55 Stage 12, Primary set point's Off Temp (°F), PSI or Volts DC (All values times 10) Read & Write
56 Stage's On Delay (Since Previous Stage Turned On) in Seconds (All values times 10) Read & Write
57 Modbus Address (Range 1 - 247) Read & Write
58 Number of Fixed Stages That Are On (Range 0 - 12) Read Only
59 0-5 VDC Input #1 Value (Temperature [°F], Pressure [PSI] or Volts [DC] (All values times 10) Read Only
60 0-5 VDC Input #2 Value (Temperature [°F], Pressure [PSI] or Volts [DC] (All values times 10) Read Only
61 0-5 VDC Input #3 Value (Temperature [°F], Pressure [PSI] or Volts [DC] (All values times 10) Read Only
62 0-5 VDC Input #4 Value (Temperature [°F], Pressure [PSI] or Volts [DC] (All values times 10) Read Only
63 0-5 VDC Input #5 Value (Temperature [°F], Pressure [PSI] or Volts [DC] (All values times 10) Read Only
64 0-5 VDC Input #6 Value (Temperature [°F], Pressure [PSI] or Volts [DC] (All values times 10) Read Only
65 To use secondary set points, 2ND terminal is grounded. (0 = not used, 1 = selected) Read Only
66 0-10 VDC Input Value are times 10, and rounded to nearest 0.1 VDC. Read Only
67 PWM Output Signal Value is in percent (Range 0% to 100%) Read Only
68 Relay sequencing mode (0 = FILO, 1 = FIFO, 2 = Binary Encode) Read & Write
69 Pressure transducer scale (0 is temp sensor, 1 is 100 PSI, 2 is 200 PSI up to 10 is 1000 PSI.) Read & Write
70 Modbus baud rate code (0 = 1200; 1 = 2400; 2 = 4800; 3 = 9600; 4 = 19,200; 5 = 38,400;
6 = 57,600 and 7 = 115,200)
Read & Write
71 Modbus parity code (38 is even, 54 is odd and 14 is no parity with 2 stop bits) Read & Write
72 If true (non-zero), reset sequencer to factory settings. Write Only
73 High speed output (Range 0 to 100) PWM duty cycle or 0-10 VDC (100 is 10.0 VDC) Read & Write
74 Low speed output (Range 0 to 100). A low speed output greater than high speed output
means as the voltage goes up, the speed goes down. (See 10 - 0 VDC Output section, page 9)
Read & Write
75 Output for motor off (Range 0 to 100). Example: 5 means PWM is 5% and VDC = 0.5
VDC
Read & Write
MODBUS Registers for the 890-DSQ Sequencer
TABLE 2B
To update any or all of the 890-DSQ Sequencer's mode, menu
and submenu parameters and numerical values remotely, using the
Modbus RTU connection, proceed with the following steps:
1) Set MODBUS RTU address, baud rate and parity for
each 890-DSQ slave sequencer installed.
2) Write to each slave using the TABLE 2A & TABLE 2B
information (pages 16 & 17) to select the 890-DSQ
Sequencer's internal register numbers and associated
data, as required, to set up the sequencer's operating
parameters and numerical values.
NOTE: Reliable operation is obtained only when using
the data values described in the Operating Modes
scetion (pages 4 thru 9) or shown in Figure 3 (pages 10
& 11).
3) Use Modbus RTU command 3 to read data from indi-
vidual or multiple internal sequencer registers.
4) Use Modbus RTU command 6 to write data to an indi-
vidual internal sequencer register.
5)Use Modbus RTU command 16 (hexadecimal 10) to
write data to individual or multiple imternal sequencer
registers.
6) Recheck all Modbus register data, not just the changed
data, and verify all the data is correct.
7) Observe the 890-DSQ Sequencer's operation, thru an
entire system's cycle, to ensure correct operation.
IMPORTANT:
After remotely updating any information the re-
mote operator MUST review ALL of the 890-DSQ
Sequencer's mode, menu, submenu and numerical
value options to 1) ensure that all of the operating
parameters, needed for the application, have been
correctly selected and 2) also ensure that any un-
needed or undesired options or numerical values
have not inadvertently been left selected.
If re-calibration of the 890-DSQ Sequencer's settings or numer-
ical values are required, due to the particulars of the application,
proceed with the following steps:
1) Power up loads (motors, heating elements etc.) and 890-DSQ
Sequencer.
2) Determine if local, remote or a combination of both local and
remote operation is to be used.
a. When local operation is desired, enter the Lockout
Code, if needed, then use the sequencer's five (5)
push buttons and the LCD screen's information to
select the settings and numerical values made avail-
able by each mode, menu and submenu screen.
Follow the Operating Methods and Operating
Modes sections (pages 3 thru 9) to update the
settings and numerical values. Also follow the Built
In Test Section (page 13).
b.
When remote operation is desired, follow the Modbus
Operation section (this page) and the Operating
Modes section (pages 4 thru 9), along with TABLES
2A and 2B (pages on 16 & 17), to update the settings
and numerical values.
c. When a combination of both local and remote opera-
tion is desired, follow the instructions in 2a) and 2b)
above. Local or remote operation can be used to
initially operate the system. The installer can then
observe and monitor the system's operation, and localy
update any parameters that allow the Sequencer to
provide the best operation for the application.
Reconnect any previously removed wires & verify the all the
wiring is correct and complete. Apply line voltage to the motors
(or SCRs and heating system), then apply 24 VAC power to the
890-DSQ Sequencer and observe the system's operation. If the
system works correctly, no operational updates are needed.
If the system does not work optimally, determine the specific
cause for the anomily and fix it. When the anomily's solution
involves an update to the 890-DSQ Sequencer's data registers,
follow the Operating Modes instructions (pages 4 thru 9) to
update the specific data register(s) needed to achieve the best
possible system operation. After the update(s) have been made,
observe the entire system's operation again, to verify the update(s)
worked.
Sequencer Re-calibration
Modbus Operation
IMPORTANT:
Remotely viewing or updating the 890-DSQ's
register data can only occur when the sequencer's
Home Screen is displayed on the LCD. If an
installer is simultaneously observing or updating
the 890-DSQ's menu, submenu or numerical
values manually, the installer must return to the
LCD's Home Screen before a remote update can
be preformed.
18
Final Sequencer Checkout
19
Operating Tips
FIGURE 9
Input Sensor Values Screen
If the installer has previously selected the 10-0 VDC output
option (10-0 VDC Output Seletion on page 9), he/she must dese-
lect the 10-0 VDC option (also within 10-0 VDC Output Seletion
on page 9), before changing the "Is Variable Stage Used?" option
(MODE 2.1 on page 4) back to No. Otherwise, the PWM and
VDC outputs will continue using the 10-0 VDC option.
The speed at which the LCD screen's values change is variable.
Holding the UP or DOWN button down causes the dislayed
value to change slowly at first and then speed up noticably. When
making large value changes hold the button down until the
displayed number is close to the desired value. Then release the
button, wait 1 second, and press the button down again to slowly
reach the desired value.
An additional Input Sensor Values LCD screen is available and
can be displayed by pressing and releasing the UP button when the
Home Screen is present on the LCD. Pressing and releasing the
UP button again returns the LCD to the Home Screen.
The Input Sensor Values screen displays the active input
temperature sensor values in °F, rounded to the nearest °F, (no
decimal point). In pressure mode, the active input transducers
values are displayed in PSI, rounded to the nearest pound (no
decimal point).
Figure 9, Input Sensor Values Screen (next column) shows the
LCD screen when temperature sensors are used as inputs. Only
the active temperature sensor values are shown on the screen. In
this case, all six (6) temperature sensors have been installed and
selected. Uninstalled or unselected temperature sensor or pres-
sure transducer inputs are not shown on the Input Sensor Values
screen. NOTE: The displayed temperature values are the actual
temperatures in °F rounded to the nearest °F.
For example:
Displayed Value Actual Temp
53 53.1°F
47 46.5°F
The top line of numbers in Figure 9 shows the temperature
inputs T1 thru T4. Temperature input T1 is on the far left of
the top line on the LCD screen. Temperature input T4 is on
the far right of the top line on the LCD screen. The bottom
line of numbers, in Figure 9, starts with the actual maximum
temperature, in °F (with decimal point) obtained from the active
temperature sensors, followed by the T5 temperature input value
and the T6 temperature input value without decimal points. A
"T:" appears before the maximum temperature to indicate the
LCD screen is displaying temperature sensor values. A "P:" appears
on the LCD screen when pressure transducer values are being
displayed on the LCD screen.
Speed Adjustment
Input Sensor Values Screen
10-0 VDC NOTE:
20
Troubleshooting Guide
1. Check wiring, review instructions.
2. Select number of fixed relay stages used.
3. Deselect 0-10 VDC input
4. Replace sequencer
1. Select correct input source.
2. Input correct set point values.
3. Select correct sequencing mode.
4. De-activate secondary set points.
1. Check wiring, review instructions.
2. Use continuously variable EC motor.
3. Select Variable Stage operation.
4. Wire EC motor to PWM output.
5. Wire EC motor to VDC output.
6. Motor protected.
7. Replace sequencer.
1. Set percentages for 10-0 VDC operation.
2. Recalculate / use correct ratio number.
3. Use proper fan blade.
4. Use correct control signal.
1. Check wiring, review instructions.
2. Select correct port.
3. Install / connect GND wire
4. Select correct slave address, baud rate &
parity.
5. Chose correct set points.
6. Correct set point values.
Relay Stages Will
Not Activate
Variable Stage's
Variable speed
EC Motors Will
Not Operate
1. Improper installation, sequencer not wired correctly.
2. Sequencer's relay stages have not been selected.
3. 0-10 VDC Input selected
4. Sequencer has been damaged
1. Incorrect sequencer input selected.
2. Incorrect set point values used.
3. Incorrect relay sequencing mode selected.
4. Secondary set points accidentally activated.
1. Variable speed EC Motor not wired correctly.
2. Selected EC motor is not a continuously variable speed motor.
3. Variable Stage operation not selected.
4. PWM operated EC motor wired to VDC output.
5. 0 - 10 or 10 - 0 VDC operated EC motor wired to PWM output.
6. EC Motor “OFF” on internal overload.
7. EC Motor not wired correctly. Sequencer damaged.
1. 10-0 VDC operated EC motor being used.
2. Variable stage to fixed stage ratio number incorrect
3. EC motor not loaded correctly
4. PWM operated EC motor being used.
1. Improper installation, sequencer not wired correctly.
2. Incorrect master computer port selected.
3. Modbus GND wire not connected
4. Incorrect slave address, baud rate or parity selected.
5. Incorrect set points chosen (primary or secondary).
6. Micro controller substituting set points for "incorrect" value.
Variable Stage
EC Motor Will
Not Modulate
Properly
Condition Cause Solution
Modbus Operation
Not Working
Properly
Relay Stages
Not Activating
Correctly
Hoffman|Controls
2463 Merrell Road, Dallas, Texas 75229 • Phone: (972) 243-7425 • Fax: (972) 247-8674 • Toll Free: 1-888-HCC-1190
www.hoffmancontrols.com Form: 173-0261-001 Rev G
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