Hussmann PCS User manual

Protocol Control System (PCS) Users Manual
Document No 0709304
Date: 5/17/2005

1. Table of Contents
1. TABLE OF CONTENTS......................................2
2. TABLE OF FIGURES..........................................4
3. DISCLAIMER.......................................................6
4. INTRODUCTION.................................................7
4.1 ORGANIZATION ................................................7
5. PCS HARDWARE................................................8
5.1 PCS CONTROLLER ...........................................8
5.1.1 Input Power.............................................8
5.1.2 Display Contrast Adjust ..........................8
5.1.3 Status LEDs.............................................8
5.1.4 DIP Switches ...........................................8
5.1.5 Mounting .................................................9
5.1.6 Fuse.........................................................9
5.1.7 Controller Wiring....................................9
5.2 PCS EXPANSION BOARD..................................9
5.2.1 Input Power...........................................10
5.2.2 Mounting ...............................................10
5.2.3 Fuse.......................................................10
5.2.4 Expansion Board Wiring.......................10
5.3 PRESSURE TRANSDUCER ................................10
5.4 TEMPERATURE SENSOR..................................11
5.5 FIELD WIRING.................................................11
6. PCS FEATURES.................................................12
6.1 OVERVIEW .....................................................12
6.1.1 Circuit Control ......................................12
6.1.2 Suction Pressure Control.......................12
6.1.3 Lighting Control....................................12
6.1.4 Discharge Pressure Control..................12
6.1.5 Alarms ...................................................12
6.1.6 Maintenance/Diagnostics......................13
7. QUICK START...................................................14
7.1.1 Display and Keypad ..............................14
7.1.2 Login......................................................14
7.1.3 Main Status Screen................................15
7.1.4 Configuration Screens...........................15
7.1.5 Viewing/Changing Suction Pressure
Setpoint 15
7.1.6 Viewing Circuit Temperatures...............16
7.1.7 Viewing/Changing Circuit Temperature
Setpoint 16
7.1.8 Determining if a Circuit is in Defrost....16
7.1.9 Forcing a Defrost..................................17
7.1.10 Alarms ...................................................17
8. CONTROLLER OPERATION......................... 19
8.1 CIRCUIT CONTROL......................................... 19
8.1.1 Defrost.................................................. 19
8.2 PRESSURE CONTROL...................................... 19
8.2.1 Switchback............................................ 19
8.2.2 Pressure Control Algorithm.................. 19
8.3 CONDENSER CONTROL .................................. 20
8.4 MENU STRUCTURE ........................................ 20
8.4.1 Status Screens....................................... 20
8.4.2 Configuration Screens .......................... 20
8.4.3 Maintenance Screens............................ 20
8.4.4 Alarm Screen ........................................ 21
8.4.5 Screen Navigation................................. 21
8.5 SCREENS........................................................ 21
8.5.1 Status Screens....................................... 21
8.5.2 Configuration Screens .......................... 22
8.5.3 Alarms................................................... 32
8.5.4 Maintenance ......................................... 32
9. PUMP STATION................................................ 33
9.1 OVERVIEW..................................................... 33
9.2 HARDWARE ................................................... 33
9.3 OPERATION ................................................... 33
9.3.1 Pump Motor.......................................... 33
9.3.2 Fluid Cooler.......................................... 33
9.4 SCREENS........................................................ 34
9.4.1 Status Screens....................................... 34
9.4.2 Configuration Screens .......................... 34
9.5 ALARMS ........................................................ 37
9.5.1 Controller Reboot................................. 37
9.5.2 Spray Pump Fail................................... 37
9.5.3 Low Speed Fan ..................................... 37
9.5.4 High Speed Fan .................................... 37
9.5.5 Pump 1.................................................. 37
9.5.6 Pump 2.................................................. 37
9.5.7 High Discharge Pressure...................... 37
9.5.8 Low Discharge Pressure....................... 37
9.5.9 Pressure Sensor Fail............................. 37
9.5.10 Inlet Temp probe Fail........................... 37
9.5.11 Outlet Temp probe Fail......................... 37
9.5.12 Ambient Temp Fail ............................... 38
9.5.13 Alarm Winter Override......................... 38
10. SUPERVISORY SYSTEM ............................ 39
10.1 OVERVIEW..................................................... 39
10.2 SUPERVISORY CONNECTION WIRING............. 39
10.3 REQUIREMENTS............................................. 39
10.4 SOFTWARE INSTALLATION ............................ 39
10.5 HARDWARE INSTALLATION........................... 40
10.5.1 RS485 Adapter...................................... 40
10.5.2 PlantVisor Software Key....................... 40
10.6 REMOTE ACCESS ........................................... 41
10.7 OPERATION ................................................... 41
10.7.1 Running the PCS Supervisor................. 41
10.7.2 Navigation ............................................ 42

Protocol Control System Users Manual 2/12/01
10.7.3 Configuration ........................................42
10.8 RUNNING THE SYSTEM...................................46
10.8.1 Troubleshooting.....................................46
10.9 PCS SUPERVISORY SYSTEM SCREENS............46
10.9.1 General Information..............................46
10.9.2 PlantVisor Engine Screens....................46
10.9.3 Supervisory Main Screen.......................47
10.9.4 Unit Main Screen...................................47
10.9.5 System Setup..........................................48
10.9.6 Suction Group/Compressor Setup.........49
10.9.7 Aux Control and Temperature Monitor.49
10.9.8 Light Ckt................................................49
10.9.9 Info ........................................................50
10.9.10 Circuits..............................................50
10.9.11 Alarms ...............................................51
11. APPENDIX A- SUPERVISORY WIRING...53
12. APPENDIX B- TROUBLESHOOTING.......54
12.1 PCS TROUBLESHOOTING ...............................54
12.2 SUPERVISORY SYSTEM TROUBLESHOOTING...54
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2. Table of Figures
Figure 1- PCS Controller.................................................8
Figure 2- Controller Wiring ............................................9
Figure 3 - PCS Expansion Board...................................10
Figure 4- Expansion Board Wiring ...............................10
Figure 5- PCS Pressure Probe .......................................11
Figure 6- PCS Temperature Probe ................................11
Figure 7- Controller Display .........................................14
Figure 8- Password Screen............................................15
Figure 9- Main Status Screen........................................15
Figure 10- Suction Group Configuration Screen...........15
Figure 11- Circuit Configuration Screen.......................16
Figure 12- Temp Setpoint Configuration Screen...........16
Figure 13- Circuit Maintenance Screen.........................17
Figure 14- Alarm Log Screen........................................17
Figure 15- Alarm Maintenance Screen..........................17
Figure 16- Alarm Confirmation Screen.........................18
Figure 17-Equal Horsepower Example .........................19
Figure 18 - PCS Menu Tree ..........................................20
Figure 19- Main Status Screen......................................21
Figure 20- Lighting Status Screen.................................22
Figure 21- Lighting Status Fields..................................22
Figure 22- Aux Processing Status Screen......................22
Figure 23- System Status Screen...................................22
Figure 24- System Configuration Screen 1 ...................22
Figure 25- System Configuration Screen 2 ...................23
Figure 26- System Configuration Screen 3 ...................23
Figure 27- System Configuration Screen 4 ...................23
Figure 28- System Configuration Screen 5 ...................23
Figure 29- System Configuration Screen 6 ...................24
Figure 30- System Configuration Screen 7 ...................24
Figure 31- System Configuration Screen 8 ...................24
Figure 32- System Configuration Screen 9 ...................24
Figure 33- System Configuration Screen 10 .................24
Figure 34- System Configuration Screen 11 .................25
Figure 35 - System Configuration Screen 12 ................25
Figure 36- System Configuration Screen 13 .................25
Figure 37- Circuit Configuration Screen 1....................25
Figure 38- Circuit Configuration Screen 2....................25
Figure 39- Circuit Configuration Screen 3....................26
Figure 40- Circuit Configuration Screen 5....................26
Figure 41- Circuit Configuration Screen 6....................26
Figure 42- Circuit Configuration Screen 7....................26
Figure 43- Circuit Configuration Screen 8....................27
Figure 44- Circuit Configuration Screen 9....................27
Figure 45- Circuit Configuration Screen 10..................27
Figure 46- Circuit Configuration Screen 11..................27
Figure 47- Circuit Configuration Screen 12..................27
Figure 48- Circuit Configuration Screen 13..................28
Figure 49- Circuit Configuration Screen 14..................28
Figure 50- Circuit Configuration Screen 15..................28
Figure 51- Copy Circuit Configuration Screen .............28
Figure 52- Suction Configuration Screen 1...................29
Figure 53- Suction Configuration Screen 2.................. 29
Figure 54- Suction Configuration Screen 3.................. 29
Figure 55- Suction Configuration Screen 5.................. 29
Figure 56- Suction Configuration Screen 6.................. 29
Figure 57- Suction Configuration Screen 7.................. 30
Figure 58- Discharge Configuration Screen................. 30
Figure 59- Lighting Configuration Screen 1................. 30
Figure 60- Lighting Configuration Screen 2................. 30
Figure 61- Lighting Configuration Screen 2A.............. 30
Figure 62- Lighting Configuration Screen 3................. 30
Figure 63- Lighting Configuration Screen 4................. 31
Figure 64- Aux Configuration Screen 1 ....................... 31
Figure 65- Aux Configuration Screen 2 ....................... 31
Figure 66- Aux Configuration Screen 3 ....................... 31
Figure 67- Aux Configuration Screen 4 ....................... 32
Figure 68- Release Configuration Screen..................... 32
Figure 69- Suction Group Maintenance Screen 1......... 32
Figure 70- Suction Group Maintenance Screen 2......... 32
Figure 71- PSC Main Status Screen ............................. 34
Figure 72- PSC Pump Status Screen............................. 34
Figure 73- PSC Pump Date/Time Screen ..................... 34
Figure 74- PSC Release Screen.................................... 34
Figure 75- PSC Password Screen................................. 35
Figure 76- PSC Configuration Screen 1....................... 35
Figure 77- PSC Configuration Screen 2....................... 35
Figure 78- PSC Configuration Screen 3....................... 35
Figure 79- PSC Configuration Screen 4....................... 35
Figure 80- PSC Configuration Screen 5....................... 35
Figure 81- PSC Configuration Screen 6....................... 36
Figure 82- PSC Configuration Screen 7....................... 36
Figure 83- PSC Configuration Screen 8....................... 36
Figure 84- PSC Configuration Screen 9....................... 36
Figure 85- PSC Configuration Screen 10..................... 37
Figure 86- PSC Configuration Screen 11..................... 37
Figure 87- PSC Alarm Screen ...................................... 38
Figure 88- Installation Screen....................................... 39
Figure 89- RS485 Adapter............................................ 40
Figure 90- PlantVisor Software Key ............................ 40
Figure 91- PlantVisor Engine Demo Mode.................. 41
Figure 92- Plantvisor Engine Screen............................ 41
Figure 93- Logon Screen.............................................. 41
Figure 94- Main Screen................................................ 42
Figure 95- Navigation Examples.................................. 42
Figure 96- Network Management Screen..................... 42
Figure 97- Site Configuration Screen........................... 43
Figure 98- Serial Line Configuration Screen................ 43
Figure 99- Modem Setup Screen.................................. 43
Figure 100- User Configuration Screen........................ 44
Figure 101- Add New User Screen............................... 45
Figure 102- Scheduler Configuration Screen ............... 45
Figure 103- Alarm Priorities Screen............................. 45
Figure 104- Device Alarm Settings.............................. 46
Figure 105- PlantVisor Engine Screen ......................... 47
Figure 106- PlantVisor Engine Detail Screen............... 47
Figure 107- PlantVisor Engine Close Screen ............... 47
Figure 108- Supervisory Main Screen.......................... 47
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Protocol Control System Users Manual 2/12/01
Figure 109- Unit Main Screen- No Alarms...................48
Figure 110- Main Screen With Alarms.........................48
Figure 111- System Setup Screen..................................49
Figure 112- Suction Group/Compressor Setup Screen..49
Figure 113- Pressure Graph...........................................49
Figure 114- Supervisory Temperature Monitor and Aux
Control Screen.......................................................49
Figure 115- Lighting Circuit Screen..............................50
Figure 116- Information Screen ....................................50
Figure 117- Circuit Setup Screen..................................50
Figure 118- Defrost Setup Screen .................................51
Figure 119- Circuit Temperature Graph........................51
Figure 120- Case Size Screen........................................51
Figure 121- Case Type Screen ......................................51
Figure 122- Supervisory Alarms Screen .......................52
Figure 123 - Supervisory Wiring...................................53
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Protocol Control System Users Manual 2/12/01
3. Disclaimer
ALL RIGHTS RESERVED
The information contained in this manual has been
carefully checked and it believed to be accurate.
However, Computer Process Controls, Inc. assumes no
responsibility for any inaccuracies that may be contained
herein. In no event will Computer Process Controls, Inc.
be liable for any direct, indirect, special, incidental or
consequential damages resulting from any defect or
omission in this manual, even if advised of the
possibility of such damages. In the interested of
continued product development, Computer Process
Controls, Inc. Reserves the right to make improvements
to this manual, and the products described herein, at any
time without notice or obligation.
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Protocol Control System Users Manual 2/12/01
4. Introduction
This document describes the Protocol Control System
(PCS). The PCS is an electronic control system designed
specifically to control all functions of the Protocol
Refrigeration System.
4.1 Organization
This document is organized into a number of sections.
The first section is an overview of the hardware. A
“quick start” section is included next to enable users to
quickly get a minimum amount of information needed to
start using the controller. A detailed section follows.
The last section describes the PCS supervisory system.
It is recommended that the user familiarize himself with
the PCS system by reading all sections of this manual
before operation.
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Protocol Control System Users Manual 2/12/01
5. PCS Hardware
The following are components of the PCS system.
1) PCS Controller
2) PCS Expansion Board
3) PCS Pressure Transducer
4) PCS Temperature Probes
This document describes the elements of the PCS
components. The schematics included with each
Protocol Refrigeration System detail the connections that
are made to the components. Refer to the schematics for
connection details.
WARNING: The Controller and Expansion board use
low voltage (24 VAC) power. However, both units have
high voltage loads connected to them. Extreme caution
should be used when servicing these units. Failure to
observe caution could lead to injury or death.
5.1 PCS Controller
The PCS Controller is a microprocessor based system
that contains a built in display, keypad and I/O (relays
termperature inputs, pressure inputs and digital inputs).
It serves as the user interface and runs the algorithms that
control the protocol refrigeration system. Additional I/O
(relays, digital inputs and temperature inputs) can be
added using the PCS Expansion Board. The controller
contains all the I/O for all compressors in the Protocol
refrigeration system.
The temperature inputs must use the PCS temperature
sensors (described below) and the pressure inputs must
use the PCS pressure probes (described below).
Figure 1 shows a picture of the PCS Controller and
identifies the different parts of the Controller.
Figure 1- PCS Controller
5.1.1 Input Power
The Controller uses 24 VAC (+/-15%, 50/60
Hz) (Class II) power at 50 VA.
5.1.2 Display Contrast Adjust
The contrast of the display can be adjusted by
pressing and holding the ENTER and ESC keys
together and pressing the UP ARROW key to
increase the contrast or the DOWN ARROW
key to decrease the contrast. Refer to
paragraph 7.1.1 for an explanation of how to
identify the keys.
5.1.3 Status LEDs
There are two LED’s on the Controller that
indicate power status. If the Yellow LED is ON
this indicates that the unit is getting power. If it
is OFF, there is either no power to the unit or
the fuse is blown. The Red LED indicates the
status of the Pressure probe power output
(Connector J2 , terminals GND and +VDC). If
the Red LED is ON, there is a fault in the probe
supply. Most likely, the pressure probe is bad
or there is a short in the cable.
5.1.4 DIP Switches
The DIP Switches on the controller should
always be in the down (OFF) position.
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Protocol Control System Users Manual 2/12/01
5.1.5 Mounting
The Controller is mounted via Din rail mount.
The Controller can be removed from the
mounting by carefully pulling on the 3 small
tabs on the bottom of the controller and rotating
the Controller up. All connectors should be
removed from the unit before removing the
Controller from the mounting.
5.1.6 Fuse
The Controller has an internal fuse. If the
Controller will not power up and you have
verified that the controller is getting input
power, you should replace the fuse. Always
replace with the same type of fuse.
5.1.7 Controller Wiring
The field wiring for the expansion board is
shown in Figure 2. Field wiring for the
controller consists of temperature probes on
inputs 4 through 8.
Figure 2- Controller Wiring
5.2 PCS Expansion Board
The PCS Expansion board is used to provide additional
I/O (relays, digital termination inputs and temperature
inputs) to the PCS Controller. Typically, the expansion
board will contain the I/O for circuits (refrigeration valve
relays, temperature inputs and defrost termination
inputs). The Expansion board contains 8 relay outputs
(Normally Open/Normally Closed outputs), 8
Temperature inputs and 8 Digital inputs.
The temperature inputs must use the PCS temperature
sensors (described below).
The Expansion board is connected to the PCS Controller
by a communications cable (Beldon 8641 or equivalent).
The PCS system supports up to 4 expansion boards. The
address of the expansion board is determined by the
wiring of inputs AD0 and AD1. Table 1 lists the
expansion board address.
Table 1- Expansion Board Addressing
Expansion
Board AD1 AD0
Board 21OPEN OPEN
Board 3 OPEN 24 VAC2
Board 4 24 VAC OPEN
Board 5 24 VAC 24 VAC
Figure 3 shows a picture of the PCS Expansion board
and identifies the different parts of the board.
1The first expansion board is referred to as board 2. The main
controller is referred to as board 1.
2InTable 1, 24 VAC means tied to “G” terminal.
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Protocol Control System Users Manual 2/12/01
Figure 3 - PCS Expansion Board
5.2.1 Input Power
The Controller uses 24 VAC (+10%/-15%,
50/60 Hz) (Class II) power at 15 VA. Note that
if using the same transformer to power the
controller and expansion board, care must be
taken to connect the G terminals on both boards
to the same side of the transformer and the G0
terminals on both boards to the same side of the
transformer.
5.2.2 Mounting
The Expansion board is mounted via standoffs.
5.2.3 Fuse
The Expansion board has an internal fuse. If the
Expansion board will not power up and you
have verified that the controller is getting input
power, you should replace the fuse. Always
replace with the same type of fuse.
5.2.4 Expansion Board Wiring
The field wiring for the expansion board
consists of the temperature probes and defrost
termination sensors. Refrigeration valve relays
are factory wired to terminal blocks. Figure 4
shows the connection points for the field wiring.
Figure 4- Expansion Board Wiring
5.3 Pressure Transducer
The PCS system uses a 4/20 milliamp pressure
transducer. Inputs are provided for reading suction
pressure (optionally a second suction group pressure) and
discharge pressure. The same type of pressure
transducer is used for reading suction and discharge
pressure. The transducer is a 2 wire connection and is
polarity sensitive (refer to the Protocol schematics for
details). The system reads 0 to 362 PSI.
The wiring for the pressure transducer should not be
routed near cables carrying high voltage.
Figure 5 shows a picture of the pressure transducer.
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Protocol Control System Users Manual 2/12/01
Figure 5- PCS Pressure Probe
5.4 Temperature Sensor
The PCS system uses an NTC type temperature sensor to
read the temperature. The temperature sensor is not
polarity sensitive. Note that the wiring for the
temperature sensor should be routed in such a way that it
is not in close proximity to any power line cables. This
will prevent invalid readings from occurring.
The temperature sensor should be placed in the discharge
air stream to give a true indication of case temperature.
Figure 6 shows a picture of the temperature sensor.
Figure 6- PCS Temperature Probe
5.5 Field wiring
All wire connections to the PCS system should be in
accordance with all applicable local and national codes.
Temperature sensors and defrost termination sensors
should be wired to the controller and expansion board
using Belden 8761, 22AWG, 2 conductor twisted
shielded pair or equivalent. This wiring should be
carefully routed away from power lines or other high
electrical noise environments.
The PCS system offers the option of using a supervisory
system where all units in the store are connected to a PC
allowing complete control of the units from the PC. For
this system each of the Controller must have a
communications card installed. The controllers must be
connected in a daisy chain fashion using Belden 8641,
24AWG, 2 conductor twisted shielded pair.This
wiring should be carefully routed away from power lines
or other high electrical noise environments
Field valve wiring should use 16/18 AWG cable
appropriate for the valve current requirements. This
wiring should not be run in close proximity to the
temperature, termination or communication wiring.
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Protocol Control System Users Manual 2/12/01
6. PCS Features
The PCS system has a number of features as defined in
the following paragraphs.
6.1 Overview
The PCS system has the following features:
6.1.1 Circuit Control
The PCS system can control up to 10 circuits.
Control consists of controlling the defrost
schedule, controlling the circuit temperature (by
using a solenoid valve), and alarming.
The controller can schedule up to 6 defrosts per
day. The defrost can be either off cycle, electric
or hot gas. Defrost can be terminated by either
time, circuit temperature or digital (Klixon)
input.
6.1.2 Suction Pressure Control
The PCS system can control up to 6
compressors. Up to two suction groups are
supported.
Control of the pressure is by PI type algorithm
for precise pressure control. The reading from
the pressure transducer is compared to the
setpoint and the appropriate action (turning
compressors on and off) is taken to maintain the
suction pressure near the setpoint. Note that
minimum on and off times and startup delays
for the compressors can be programmed.
6.1.3 Lighting Control
Two circuits are provided for lighting control.
The lighting circuits can be turned on and off by
a 7 day schedule with one on and one off time
per day.
6.1.4 Discharge Pressure Control
The PCS system can be used to control
condensor fans. The fans are cycled in response
to the discharge pressure setpoint and the
current discharge pressure reading. The
controller uses a PI algorithm to maintain
smooth discharge pressure.
If the Protocol system uses a fluid cooler instead
of an air cooled condenser, a separate controller
will be used to control the Pump Station (refer
to the section on Pump Station Control).
The PCS controller will provide alarming on
the discharge pressure input, but will not
provide direct control in this case.
6.1.5 Alarms
The PCS system keeps an alarm log with 16
entries. The alarm log displays the date and
time that the alarm occurred, the type of alarm
and whether the alarm is ACTIVE or has been
ACKNOWLEDGED. When an alarm occurs,
the alarm relay will activate, the ALARM key
will turn RED and the Alarm menu will
automatically be displayed. The alarm relay
will remain activated and the ALARM key will
remain RED until the alarm is
ACKNOWLEDGED.
Alarms are provided for the following
conditions:
6.1.5.1 High/Low Circuit Temperature
An alarm is signaled if the circuit temperature is
too high or too low (as determined by the alarm
setpoints).
6.1.5.2 Defrost Termination
An alarm is signaled if a defrost is set up to
terminate by temperature or digital termination,
but terminates by the maximum time instead.
This can indicate that there may be some type of
problem with the case (ice build up) or the
termination sensor.
6.1.5.3 High/Low Suction Pressure
If the suction pressure is above or below the
limits (as defined by the alarm setpoints) this
alarm will be signaled.
6.1.5.4 High Discharge Pressure
If the discharge pressure is above the limit (as
defined by the alarm setpoint) this alarm will be
signaled. Note that the discharge pressure alarm
will automatically clear (but will remain in the
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Protocol Control System Users Manual 2/12/01
alarm log) if the discharge pressure falls below
the alarm limits.
6.1.5.5 Sensor Failures
If a temperature or pressure probe failure
occurs, this alarm will be signaled. The alarm
will provide details as to what sensor has failed.
6.1.5.6 Compressor Proof Failures
This alarm will be signaled if a compressor
proof fails. Note that proofing is optional in
the Protocol refrigeration system. Refer to the
Protocol schematics for details.
6.1.5.7 Compressor General Alarms
This alarm will be signaled if a general alarm
occurs for a compressor. A general alarm
occurs when the digital input associated with
the compressor is active. There is one digital
input for each compressor. The digital input
will be activated when the oil level sensor trips,
there is a high pressure cutout or the discharge
temperature is to high. See the Protocol
schematic for details.
6.1.5.8 Phase Loss
This alarm will be signaled if the controller
detects a phase loss.
6.1.5.9 Controller Reset
If the controller resets due to an interruption of
power, this alarm will be signaled when power
is restored
6.1.6 Maintenance/Diagnostics
The controller provides the following
capabilities for maintenance:
6.1.6.1 Force Defrost
A circuit can be forced to perform a defrost or
to cancel a defrost in progress. Note that if a
defrost is forced, the defrost will terminate
normally as defined by the circuit setpoints.
6.1.6.2 Force Compressors
A compressor can be forced on or off. Note that
the user must be logged in to force the
compressor on or off and the compressor state
will return to normal when the controller logoff
timeout occurs.
6.1.6.3 Compressor Run Time
The run time (in hours) for each compressor is
stored. The run time can be cleared if a
compressor is replaced.
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Protocol Control System Users Manual 2/12/01
7. Quick Start
This section of the manual provides a quick overview of
the operation of selected features of the controller. It is
intended to provide an overview of the most used
features. Refer to the Controller operation section for
more details.
7.1.1 Display and Keypad
The controller’s user interface consist of a 4x20
LCD display with a 6 button keypad. The
display/keypad are used to see status
information on the controller and also to change
setpoints. Figure 7 shows the display and
keypad of the controller.
Figure 7- Controller Display
Table 2- Controller Key Functions
Key Name Function
ALARM Enters the alarm
menu or returns to
original menu from
alarm menu
PROGRAM Enters maintenance
menu (depends on
current screen)
ESCAPE Return to Main
status screen (from
any screen) or move
to other status
screens (from Main
status screen)
UP
ARROW 1) On Main status screen- Moves
between status
fields
2) On other
screens- Used
to enter a value
DOWN
ARROW 1) On Main status screen- Moves
between status
fields
2) On other
screens- Used
to enter a value
ENTER 1) On Main status
screen- Enters
the
configuration
menus for a
given field
2) On other
screens- Used
to move
between fields
and to accept a
value.
7.1.1.1 Cursor
Each screen can have one or more fields. The
active field will have a cursor on the first
character of the field. The cursor will alternate
between a block and the normal character for
the field.
7.1.2 Login
Certain actions (changing setpoints, forcing
defrosts, etc.) require the user to log on to the
controller. This requires the user to enter a
password. When you must log in to perform the
action, a logon screen will pop up and you will
be prompted to enter the password. When this
happens, enter the numeric password (using the
UP or DOWN ARROW keys) then press the
ENTER key. If the password is correct the
login screen will disappear and you will be able
to perform the action. If the password is not
correct, you will not be allowed to perform the
action and the logon screen will appear again
after you press the ENTER key. Once you have
logged in, you will not have to enter the
password again unless the controller times out
and logs out. The time out will occur if you do
not press any of the keys for 5 minutes. At that
point, the controller will log you out and return
to the main status screen.
The factory default password is “0000” and it
can be changed by an authorized user.
Figure 8 shows the password screen.
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Protocol Control System Users Manual 2/12/01
Figure 8- Password Screen
7.1.3 Main Status Screen
Figure 9 shows the main status screen. This
screen is displayed when the controller is first
powered on. This screen will also be displayed
if there are no keys pressed for a period of 5
minutes.
Figure 9- Main Status Screen
The first row on this screen shows the current
pressure reading for suction group 1 and (if
configured for two suction groups) suction
group 2. The second row shows the current
reading for the discharge pressure. The bottom
two rows show the circuit status. The numbers
1 to 10 on the third row represent circuit
numbers 1 to 10. On the last row there will be
either a “-“, “R”, “D” or “S” under each circuit
number. If a “-“ is present, this means that the
circuit has not been configured. If a “R” is
present, this means that the circuit is currently
in refrigeration mode. If a “D” if present, this
means that the circuit is in defrost. If an “S” is
present, it means that the circuit has temperature
control enabled and the circuit temperature is
currently satisfied.
To return to the main status screen from a
configuration or maintenance screen, press the
ESCAPE key once. To return to the main status
screen from another status screen, press the
ESCAPE key until the Main status screen is
displayed. Depending on which status screen
you are currently in, you might have to press the
ESCAPE key several times.
7.1.4 Configuration Screens
There are several configuration screens. In
general, these screens provide more detailed
status information and also contain setpoints.
Typically, there are several configuration
screens for a given function (circuit
configuration, for example). When a
configuration screen is first entered, the cursor
rests in the upper left hand corner of the screen.
If you press the UP or DOWN ARROW keys
with the cursor in the resting position, the next
or previous configuration screen will be
displayed.
7.1.4.1 Active Fields
Each configuration screen typically consists of a
number of fields. A field can be a setpoint or
any other area where a value can be changed.
Pressing the ENTER key with the cursor in the
resting position will advance the active field to
the first field on the screen. At this point, the
value of the field can be changed (using the
ARROW keys) or pressing the ENTER key
again will advance to the next field. If the value
of the field is changed, the ENTER key must be
pressed to accept the value and move to the next
field. Continue pressing the ENTER key until
the cursor returns to the upper left corner of the
screen.
7.1.5 Viewing/Changing Suction Pressure
Setpoint
To view or change the suction pressure setpoint,
you must enter the suction configuration screen.
To do this from the Main status screen, use the
ARROW keys to move the active field to either
Suction Group 1 or Suction Group 2. Now
press the ENTER key. The Suction Group
configuration menu will now be displayed.
Figure 10- Suction Group Configuration Screen
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The first row has the group number that you are
viewing. The name of the suction group is also
displayed on the top row. The next row has the
suction pressure reading (in PSI). The next row
has the suction setpoint (in PSI). The last row is
an indication of how many compressors (that
are assigned to this suction group) are currently
on. In this example, there are 3 compressors
assigned to the group and 1 is on.
If there are two suction groups, you can look at
the second suction group by pressing the
ENTER key to put the cursor on the group
number, then pressing the UP ARROW key to
change the value of the field to 2, then press the
ENTER key. The other active field on the
suction configuration screen is the suction
setpoint. Press the ENTER key to advance from
the suction group field to the setpoint field. The
value can now be changed by pressing the
UP/DOWN ARROW keys. After the new value
has been entered, press the ENTER key to
accept. Press the ENTER key once more to
return the cursor to the resting position. The
setpoint has now been changed.
7.1.6 Viewing Circuit Temperatures
In order to view circuit temperatures, you must
enter the circuit configuration screen. To do
this from the Main status screen, press the
DOWN ARROW key until the cursor is on the
circuit number you would like to view. Then
press the ENTER key. The Circuit
configuration screen will now be displayed.
Figure 11- Circuit Configuration Screen
The first row displays the circuit number
(similar to the suction group number in the
suction group configuration screen) and the
name of the circuit. The next row displays the
current state of the circuit. “REFR” indicates
refrigeration. “DEFR” indicates defrost.
“SATISFIED” indicates that the circuit has
temperature control enabled and the circuit
temperature is currently satisfied. The third row
shows the current temperature for the circuit.
Note that there can be up to three temperature
probes defined for a circuit and the number
displayed on this screen is the combination of
the three.
By pressing the ENTER key on this screen, you
will move the cursor to the first field which is
the circuit number. You can change the circuit
number you are currently viewing by using the
UP or DOWN ARROW keys to change the
circuit number. The temperature for the
selected circuit will automatically be displayed
(without the need to press the ENTER) key.
There may be a slight delay (up to 2 seconds)
for the display to update with the temperature
for the new circuit.
7.1.7 Viewing/Changing Circuit Temperature
Setpoint
To view or change the circuit temperature
setpoint you must enter the circuit configuration
screen. With the cursor in the resting position
(upper left hand corner), press the DOWN
ARROW key two times and a screen will be
displayed with the temperature setpoint.
Figure 12- Temp Setpoint Configuration Screen
To change the circuit temperature, press the
ENTER key twice to make the Temp Setpt the
active field. Use the UP or DOWN ARROW
keys to change the value. Press the ENTER key
to accept the new value. Note that the active
field will automatically go to the Temp Ctrl
field. Press the ENTER key again to return the
cursor to the upper left corner (resting position).
7.1.8 Determining if a Circuit is in Defrost
To determine if a circuit is in defrost you can
look at the circuit’s status in the Main status
screen (“D”) or in the circuit configuration
screen (“DEFR”).
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7.1.9 Forcing a Defrost
To force a circuit into defrost, you must be in
any of the circuit configuration screens. From a
Circuit configuration screen, press the
PROGRAM key. The Circuit maintenance
screen will be displayed.
Figure 13- Circuit Maintenance Screen
The Circuit maintenance screen displays the
circuit number and name on the top row. The
current circuit state is displayed on the second
row. The third row contains a field called
“Force Defr. On:”. By moving the cursor to this
field (using the ENTER key) and pressing the
UP ARROW key the “NO” will be changed to a
“YES”. Press the ENTER key to accept the
change and a forced defrost will be started.
Note that the defrost will terminate in the
normal way (according to the circuit setpoints).
Likewise, you can cancel a defrost by moving
the cursor to the field that says “Force Defr.
Off:” and changing the “NO” to “YES” with the
ARROW key and pressing ENTER.
7.1.10 Alarms
If an alarm occurs, the controller will
automatically display the alarm log screen and
the ALARM key will turn RED. The alarm
screen can also be enter from any other screen
by pressing the ALARM key.
Figure 14- Alarm Log Screen
The Alarm screen displays the date and time
when the alarm occurred on the top row. The
next row shows the alarm number (1 to 16) and
the Status (either active (ACT) or acknowledged
(AKN). The last row gives a description of the
alarm.
To view other alarms use the UP or DOWN
ARROW keys to display other alarms that are in
the alarm log.
7.1.10.1 Acknowledging Alarms
To acknowledge an alarm you must be in the
Alarm maintenance screen. To enter the Alarm
maintenance screen, first enter the alarm screen,
then press the PROGRAM key. The Alarm
maintenance screen will be displayed.
Figure 15- Alarm Maintenance Screen
The alarm maintenance screen has two fields.
Press the ENTER key to move to the first field
that says “Reset current alarm”. Press the UP
ARROW key and the “NO” will change to
“YES”. Press the ENTER key to accept the
entry and the alarm current active alarm will be
acknowledged. The controller will
automatically return to the alarm screen.
Note that there may be more than one active
alarm. If you have cleared the alarm and the
ALARM key is still RED, use the ARROW
keys to determine if there are other alarms in the
alarm log that are active. If so, use the
ARROW keys to display the active alarm then
acknowledge the alarm as described in the
preceding paragraph.
7.1.10.2 Clearing the Alarm Log
To clear the alarm log, enter the alarm
maintenance screen as described in paragraph
7.1.10.1. Press ENTER twice to move the
cursor to the “Reset alarm log:” field. Use the
ARROW keys to change the “NO” to “YES”.
Immediately a confirmation screen will pop up
asking you to confirm that you would like to
clear the alarms. Pressing the ESCAPE key will
cancel the operation and return you to the alarm
screen. Pressing the ENTER key will result in
the alarm log being cleared.
Note: Use caution when clearing the alarm log.
Once cleared, alarm entries cannot be
retrieved.
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Figure 16- Alarm Confirmation Screen
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8. Controller Operation
The basic operation of the controller is described in the
following paragraphs. An overview of the menu
structure is given, the more detailed information for each
screen is presented. Where applicable, additional
information about the control algorithms, etc. are
provided.
8.1 Circuit Control
The PSC controller provides circuit control for up to 10
circuits. Each circuit can have up to 3 temperature
probes for temperature monitoring. A relay can be
assigned for temperature control. Each circuit also has a
defrost schedule that controls defrost.
8.1.1 Defrost
There are three types of defrost supported by the
controller, HOT GAS, ELECTRIC and OFF
CYCLE. Refer to the Protocol schematics for
details of the wiring for each type of defrost.
8.2 Pressure Control
The PCS controller provides control of suction pressure
by cycling compressors on and off to meet the load
requirements. Up to 6 compressors are supported for a
suction group. The controller will support 1 or 2 suction
groups.
8.2.1 Switchback
Switchback is a mechanical backup mode of the
PCS. This occurs when a hard failure occurs in
the controller and it is unable to run. When this
occurs, the switchback relay (controller point 7)
will open (normally, this relay is held close).
This willcause the SBA relay to open and some
of the compressors will be powered through the
Normally Closed contacts of the SBA relay and
the Low Pressure Control. Refer to the Protocol
schematics for more detail.
8.2.2 Pressure Control Algorithm
There are two basic pressure control algorithms
used in the Controller. If all compressors have
the same horsepower, an equal horsepower
algorithm is used that equalizes run times
between compressors. If there are different
horsepowers, a different algorithm is used. The
algorithms are described in the following
paragraphs.
8.2.2.1 Equal Horsepower compressors
If the compressors all have the same
horsepower, the controller uses the deadband
and setpoint to determine what compressors
should be on. “Bins” are created which
determine when a compressor is turned on and
off. One Bin is created for each compressor.
The size of the Bin is determined by the
deadband divided by the number of
compressors. An example is shown in Figure
17. In this example, the setpoint is 50 psi, the
deadband is 16 psi and there are four
compressors. As the pressure increases (going
toward the right side), more compressors are
turned on. As the pressure decreases (going
toward the left side) compressors are turned off.
Figure 17-Equal Horsepower Example
Note that there are other setpoints which affect
the minimum on and off times for the
compressors (See Figure 30 and Figure 31).
The above example shows the effect of the
Setpoint and Deadband in controlling the
suction pressure. This is basically
“Proportional” control. The controller
incorporates an additional parameter that is used
for PI (Proportional + Integral) control (See
Figure 25). This parameter is called
“Integration time” (See Figure 54). For PI
control, the controller will add (or subtract) a
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small amount to the actual pressure reading
before determining how many compressors to
turn on. The Integration time is the length of
time (in seconds) it takes for the controller to
add an error equal to the setpoint minus the
actual pressure reading.
Using the example shown is Figure 17, assume
that the actual pressure reading is 52 psi and the
integration time is 10 seconds. The error is (52
psi – 50 psi) 2 psi. In 10 seconds, 2 psi will be
added to the actual pressure and the controller
will calculate the compressors to turn on based
on a pressure of (52 psi + 2 psi) 54 psi. This is
at the bottom of Bin 3 so compressor 1,2 and 3
would be turned on at this point.
8.2.2.2 Unequal Horsepower compressors
If a controller has unequal compressors, the
algorithm is slightly different than the above
example. First the controller calculates the
number of steps it has available. For example,
if there are two compressors, the first being a 2
HP and the second being a 3 HP, there are 3
steps available (2 HP, 3 HP and 5 HP). The
controller then calculates a % capacity required
which is based on the error between the actual
reading and the setpoint. This error is divided
by the deadband and converted to a percentage
(0 to 100%). The percentage is applied to the
steps and the closest match is used. No runtime
equalization is performed for unequal
horsepower compressors.
Note that if PI control is used, an integration
error amount is added to the actual reading as
described above.
8.3 Condenser Control
The controller has the capability to control an air cooled
condenser (see Figure 32 and Figure 33). The condenser
control is very similar to the equal horsepower pressure
control with the number of compressors being the
number of fans. Note that the control of the fans is
Proportional control only.
8.4 Menu Structure
The screens on the controller consist of 4 basic types of
screens. They are Status screens, Configuration screens,
Maintenance screens and the Alarm screen. Figure 18
shows a menu tree that shows these different types of
screens. Each screen type is discussed in the following
paragraphs.
Figure 18 - PCS Menu Tree
8.4.1 Status Screens
Status screens are display only screens. They
provide information about a particular function
of the controller (for example, Suction
pressure). They also serve as the entry into the
configuration screens. There are 5 status
screens. They are shown on the top row of
Figure 18. They are the Main Status, Lighting
Status, Aux Processing Status, System Status
and Release Info and Status. Each of the
screens will be described in detail later in this
document.
8.4.2 Configuration Screens
Configuration screens are screens that show
more detailed status and also have setpoints.
There are six basic types of configuration
screens: Circuit, Suction Group, Discharge,
Lighting, Aux Processing and System. These
screens are shown on row 2 in Figure 18. The
configuration screens also serve as an entry to
the maintenance screens.
Note that Figure 18 only shows one block for
each type of configuration screen. Each block
may represent many screens. For example,
there are six configuration screen for Suction
Group setup.
8.4.3 Maintenance Screens
Maintenance screens are shown on the third row
of Figure 18. Maintenance screens allow you to
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