Mod-tronic MT300 User manual

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MT300
Three Channel Temperature Monitor
User Manual

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Table of Contents
1 Introduction .......................................................................................................................................... 4
2 Conventions .......................................................................................................................................... 4
3 Installation ............................................................................................................................................ 5
3.1 Mounting................................................................................................................................... 5
3.2 Wiring ........................................................................................................................................ 6
3.2.1 Controller Power......................................................................................................... 7
3.2.2 Inputs .......................................................................................................................... 7
3.2.3 Outputs ....................................................................................................................... 8
3.2.4 Serial Communication................................................................................................. 9
4 Configuration ...................................................................................................................................... 10
4.1 Non-Volatile Configuration Storage ........................................................................................ 10
4.2 Primary Configuration ............................................................................................................. 10
4.2.1 ...................................................................................................................... 12
4.2.2 ...................................................................................................................... 12
4.2.3  ........................................................................................................................ 12
4.2.4 ...................................................................................................................... 12
4.2.5  .......................................................................................................................... 13
4.2.6 ...................................................................................................................... 14
4.2.7  through ................................................................................ 14
4.2.8 ...................................................................................................................... 16
4.2.9  ...................................................................................................................... 17
4.2.10  ...................................................................................................................... 17
4.2.11  ...................................................................................................................... 17
4.2.12  ........................................................................................................................ 18
4.2.13  .......................................................................................................................... 18
4.2.14 ...................................................................................................................... 19
4.2.15 ...................................................................................................................... 20
4.2.16  ........................................................................................................................ 21
4.3 Secondary Configuration......................................................................................................... 21
4.3.1 through  ................................................................................. 21
5 General Usage..................................................................................................................................... 22
5.1 Operation Modes .................................................................................................................... 22

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5.1.1 Monitoring Mode...................................................................................................... 22
5.1.2 Peak Display Mode.................................................................................................... 23
5.1.3 Setup Mode............................................................................................................... 24
5.1.4 Test Mode ................................................................................................................. 24
5.2 Access Restrictions .................................................................................................................. 24
5.3 Special Functions..................................................................................................................... 26
5.3.1 Recovery.................................................................................................................... 26
5.3.2 Error Reporting ......................................................................................................... 26
5.3.3 USB Reset .................................................................................................................. 26
6 MODBUS ............................................................................................................................................. 27
6.1 Holding Registers..................................................................................................................... 27
6.2 Input Registers......................................................................................................................... 31
6.3 Value Format Key .................................................................................................................... 31
7 Specifications ...................................................................................................................................... 40
7.1 Inputs....................................................................................................................................... 40
7.1.1 Power ........................................................................................................................ 40
7.1.2 Sensors ...................................................................................................................... 40
7.2 Outputs.................................................................................................................................... 40
7.2.1 4-20mA loop.............................................................................................................. 40
7.2.2 Relays ........................................................................................................................ 40
7.3 Communication ....................................................................................................................... 41
7.3.1 RS-485 ....................................................................................................................... 41
7.3.2 USB............................................................................................................................ 41
7.4 General .................................................................................................................................... 41
7.4.1 Accuracy.................................................................................................................... 41
7.4.2 Dimensions................................................................................................................ 41
7.4.3 Weight....................................................................................................................... 41
7.4.4 Environmental........................................................................................................... 41
7.4.5 Construction.............................................................................................................. 41
7.4.6 Approvals .................................................................................................................. 41
7.4.7 Factory Defaults ........................................................................................................ 41
8 Glossary............................................................................................................................................... 42
9 Change Log.......................................................................................................................................... 43

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1 Introduction
The MT300 is a universal, three-channel temperature monitor capable of utilizing any combination of the
supported sensor types. Three relay outputs and an internal buzzer are individually configurable to be
tripped by one or more sensor inputs. The included 4-20mA output is fully configurable and may be loop
powered or internally powered. An RS-485 interface and USB port use the MODBUS protocol to configure
the unit as well as read the configuration, sensor values, and peak values. However, all configuration and
available values are accessible via the intuitive front panel interface. Celsius and Fahrenheit scales are
supported.
Separate electrical isolation is provided on the 4-20mA loop, RS-485, and sensor inputs for compatibility
with a wide range of installation environments.
2 Conventions
Several different typestyles are used throughout this manual to make it easier to convey whether the text
refers to a button, indicator, numeric display, output, etc.
In general, if a word or phrase is in all caps (LIKE THIS) it means that it refers to the name of a button or
single LED indicator on the MT300 front panel. Exceptions to this are acronyms such as USB and MODBUS.
If a word or phrase is first letter capitalized (Like This) it means that it refers to the name of a feature, such
as Fan Exerciser, or an input or output, such as Channel 1 or Fan Relay.
If a word or phrase is in an LED display font () it means that it refers to something displayed on
the numeric display.
If a value is preceded by “0x”, that value is in hexadecimal; other numbers should be assumed to be
decimal.
The usage of the words “alarm” and “trip”, in particular, regardless of capitalization, could be confusing.
These two words are industry standard terms for relay outputs on products such as the MT300.
Alarm could refer to the Alarm Relay output, front panel ALARM indicator, or the audible alarm (Buzzer).
However, when referring to the relay output, it is explicitly written as such. When referring to the front
panel indicator, capitalization will be used as previously described to prevent confusion.
Trip can refer to the Trip Relay output, the front panel TRIP indicator, the action of a setpoint being
exceeded, or describing the group of settings that determine a setpoint, and what happens when that
setpoint is exceeded, which is referred to as “trip settings”. Again, the previously described convention
will be used to clarify the intended meaning.
Because of the Reverse Acting Relay feature, specific terms are used to indicate whether a relay’s coil is
actually powered, or if that relay output is in the trip state regardless of the Reverse Acting Relay settings.
If referring to whether a relay’s coil is powered, “energize” will be used. If referring to if a relay output is
in the trip state, “engage” will be used.
If a relay output is engaged, the associated front panel LED will light, however, whether the relay is
energized will depend on the Reverse Acting Relay settings.

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3 Installation
There are no jumpers or user-accessible connections inside the MT300. Instead, it is suggested that the
user determines whether the C or F scale is preferred and set this before further configuration since the
MT300 will not convert existing settings when the scale is changed.
3.1 Mounting
The MT300 should be installed in a rectangular cutout of dimensions 5.6” x 9.0”, or 142mm x
229mm. The dimensions of the MT300 are shown in Figure 1 for reference. It’s easiest to place the
MT300 in the cutout, then mark or directly drill the screw mount holes.
The mounting screws/bolts should be tight enough to compress the foam gasket so as to prevent
debris from entering behind the MT300.
Figure 1

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3.2 Wiring
The rear panel is shown in Figure 2 and provides a visual guide of the terminal block connections.
Each connection is detailed in following sections.
Figure 2

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3.2.1 Controller Power
The MT300 is available in AC and DC models. While the external connections appear
identical, care must be taken to properly connect the appropriate power supply.
The power input for both the AC and DC model is electrically isolated from the rest of the
MT300 circuitry.
3.2.1.1 AC Model
On AC models, the line and neutral must be connected to the L/+ and N/-
terminals, respectively. The remaining connection is earth ground. It is
imperative that the earth ground terminal be properly connected. While the unit
will function without it, failure to do so is a potential shock hazard, may cause
reduced performance, and puts the MT300 at risk for damage due to ESD and
consequently will void the warranty.
3.2.1.2 DC Model
On DC models, the positive and negative must be connected to the L/+ and N/-
terminals, respectively. As with the AC model, the remaining connection is earth
ground, and it is imperative that the earth ground terminal be properly
connected. While the unit will function without it, failure to do so is a potential
shock hazard, may cause reduced performance, and puts the MT300 at risk for
damage due to ESD and consequently will void the warranty.
3.2.2 Inputs
The MT300 can use any combination of supported sensors which are listed in 7.1.2.
The sensor inputs are collectively isolated from the rest of the device, but are not isolated
from each other. Therefore, care must be taken to not create a situation where a voltage
differential can occur between sensors. This is generally an issue only if grounded
thermocouples are used since most RTDs are electrically isolated from the sensor casing.
Each sensor channel has four terminals. Terminals A through C are sensor inputs, and
terminal D is an earth ground connection for sensor lead wire shields. In general, shielded
and twisted pair sensor wires are the best for electrically noisy environments. In addition,
RTDs are generally more immune to noise than thermocouples, and offer better accuracy.
If a shield is provided on a sensor lead, it should be grounded at only one end for best
performance. Which end to ground is usually determined through trial and error since
otherwise it is extremely difficult to determine. Terminal D is provided for this purpose if
the sensor is grounded at the MT300 end.
3.2.2.1 RTDs
Either two-wire or three-wire RTDs may be used. Using three-wire RTDs will allow
the MT300 to automatically compensate for wire resistance as long as all three
wires have the same resistance (i.e. same wire gauge and length).

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When using two-wire RTDs, connect terminals B and C together with a short
jumper, then connect the RTD to terminal A and the junction of B and C. Be aware
that the lead wire resistance on a two wire RTD will be included in the
measurement, and therefore, will be less accurate.
When using three-wire RTDs, the uniquely colored wire is usually the one to
connect to terminal A, and the remaining two similar colored wires should be
connected to terminals B and C. If in doubt, an ohmmeter may be used to
determine which two sensor wires are connected together at the sensor end.
These are the wires that should connect to terminals B and C.
3.2.2.2 Thermocouples
The thermocouple’s positive lead should be connected to terminal A, and the
negative lead should be connected to terminal C. Generally the negative wire on a
thermocouple is red. Terminal B must remain unconnected.
3.2.3 Outputs
3.2.3.1 Relays
Three relay outputs are available: two SPDT relays and one SPST relay. It should
be noted that although the relays have specific names, the function of each relay is
fully programmable with the exception of the Fan relay, which in addition is
permanently linked to the MANUAL FAN button and the Fan Exerciser.
The terminal assignments are indicated on the rear cover of the unit; COM =
Common, NO = Normally Open, and NC = Normally Closed.
3.2.3.2 4 –20mA Loop
A 4 –20 mA output is provided on the MT300. This output will pass a current
between 4 and 20 mA to represent one of the sensor inputs. The output will fall as
low as 3.8mA or as high as 21mA during normal operation in which the loop
output has reached beyond the range defined by the user. The output may also
fall to either 3.5mA or 23mA to indicate a sensor out of range.
The loop may be configured to be external loop-powered or powered by the
MT300.
The loop output is electrically isolated from the rest of the MT300 except when
internal loop power is selected. When internal loop power is selected, it is
electrically connected to the power supply of the MT300, and therefore
electrically connected to the USB port, while other terminals on the MT300 remain
electrically isolated from the loop.

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In environments harboring a high amount of EMI or electrical interference, the 4-
20mA loop cable will need to be wrapped around a ferrite to meet the stated loop
accuracy. This ferrite is generally required only if the 4-20mA loop is used and is in
very close proximity to devices generating a high amount of EMI (such as motors
and radio transmitters). An indication this ferrite is required would be if the 4-
20mA output fluctuates wildly. If the 4-20mA loop output is stable, there is no
need to add anything. Please contact Mod-Tronic if you believe you require this
part and one will be provided free of charge.
For reference, the recommended part is Würth Elektronik 7427153.
3.2.4 Serial Communication
The MT300 includes an RS-485 and USB interface, both of which communicate using the
MODBUS protocol. Either interface may be chosen to communicate with the unit, but both
cannot be used simultaneously. Both interfaces accept the same commands and have
access to the same registers, but USB will typically be used for an easy connection to a
computer, while RS-485 will typically be used when multiple MODBUS devices must be
connected in a network, when other standalone MODBUS devices communicate with the
MT300, or when long bus length is required.
Two LEDs are located near the USB jack; one is labeled COMM and the other is labeled
ERROR. The COMM LED will blink when the selected interface, RS-485 or USB, is sending or
receiving data. This LED will blink when the selected interface receives anything, including
invalid data. The ERROR LED will blink if the MT300 receives a valid MODBUS message with
a function code that isn’t supported by the MT300.
3.2.4.1 RS-485
RS-485 is a differential signaling method that provides high reliability over long
distances and multiple devices on a single network, over a single twisted pair. The
MT300 has two identical sets of terminals for RS-485 connections, each set
containing terminals A, B, and S. Both “A” terminals are electrically identical and
are the non-inverting connections, while both “B” terminals are electrically
identical and are the inverting connections. The “S” terminals are also electrically
identical and are for the cable shield which should be connected in one location
only. A 120Ωtermination resistor will typically be connected across terminals A
and B in each end device in an RS-485 network.
A MODBUS slave ID and baud rate must be selected in the configuration before
the RS-485 interface can be used.
The RS-485 interface is electrically isolated from other MT300 circuitry.
3.2.4.2 USB
The USB interface provides a quick and convenient method of connecting the
MT300 to a computer when an RS-485 interface is not available. The commands
and capability are identical to the RS-485 interface; the USB interface appears as a
COM port to Windows so it may be possible to use some third-party Windows RS-
485 applications with USB.

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In order to use the USB interface, a MODBUS slave ID must be selected and the
baud rate must be set to “”. The Windows application must be set to the COM
port assigned to the USB connection, baud rate set to 19.2K, and no flow control.
The USB interface is not electrically isolated.
The Windows driver is on the included CD under “MCP2200\Driver Installation
Tool”. From there, choose “x86” or “x64” depending on if your Windows
installation is 32 bit or 64 bit, respectively.
4 Configuration
To configure the MT300, Configuration Mode must be entered. To do this, press and hold the
ENTER/MENU button. If no password is set, the Primary Configuration will immediately be presented and
the first menu option, , will be displayed. Otherwise, if at least the Primary Password is set, the
MT300 will ask for the password by displaying . Use the UP and DOWN buttons to change the first
digit to the desired number, and then press ENTER/MENU to accept and move to the next digit. Continue
until all four digits have been set.
If the entered password does not match either the Primary or Secondary Password,  will
momentarily display and will revert back to Monitoring Mode. If the entered password matches the
Primary Password, access to the Primary Configuration will be granted; all configuration settings will be
available. The first menu option, , will be initially displayed. (Note: the front panel TEST button is
protected by the Primary Password)
If the entered password matches the Secondary Password, access to the Secondary Configuration will be
granted; only the trip setpoints will be available. In this case the first menu option of the “setpoint-only
menu”, , will be initially displayed.
Should the user set the Primary Password and the Secondary Password to the same code, the MT300 will
behave as if the Secondary Password is disabled (i.e. set to ).
4.1 Non-Volatile Configuration Storage
All configuration settings are stored to non-volatile memory at the point of exiting Configuration
Mode. When power to the MT300 is lost, or a reset occurs, the configuration is kept intact.
4.2 Primary Configuration
Use the UP and DOWN buttons to cycle through the base menu options, then use the ENTER/MENU
button to select. The specifics of each base menu option are detailed in the following sections. See
Figure 3 for the list and order of the base menu options.
CANCEL may be pressed at any time to back up one menu level at a time. Once a specific setting is
confirmed with the ENTER/MENU button, it is saved and the user may press CANCEL to drop back a
menu level, or pressed repeatedly until the MT300 exits Setup Mode.
If no buttons are pressed while in Setup mode for two minutes, Setup will automatically exit. Any
changes made will be saved. The automatic exit function simulates a press of the CANCEL button.

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















a
a
Y


R
T

Figure 3

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4.2.1 
This is used to set sensor types. Initially Channel 1 will be displayed, as indicated by on the
left digit, followed by the sensor type which may be , , , , or
, which corresponds to sensor off, platinum 100Ω, platinum 1000Ω, thermocouple type
K, and thermocouple type E, respectively. Press the UP and DOWN buttons to cycle through
the sensor types until the appropriate one is displayed, then press ENTER/MENU to confirm.
Channel 2 will then be displayed, and the process is repeated until all three channels have
been set. After Channel 3, the display will revert to the base menu list.
4.2.2 
This sets an optional offset to the measured temperature of each channel. Initially Channel
1 will be displayed, as indicated by on the left digit, followed by the offset value. Press the
UP and DOWN buttons to change the offset, then press ENTER/MENU to confirm. Channel 2
will then be displayed, and the process is repeated until all three channels have been set.
After Channel 3, the display will revert to the base menu list.
Applying an offset may be useful to compensate for a sensor offset, or in effect, change
multiple setpoints by only changing the offset value.
It is possible to measure temperatures beyond the MT300’s specified range by applying an
offset since only the displayed temperature is prevented from exceeding the rated range,
however, accuracy in this case is not guaranteed.
4.2.3 
This sets the scale to Celsius or Fahrenheit. Celsius is represented as , and Fahrenheit as .
Once ENTER/MENU is pressed to confirm the setting, the display reverts to the base menu
list. It is suggested the user determines whether the C or F scale is preferred and set this
before further configuration since the MT300 will not convert existing settings when the
scale is changed.
4.2.4 
This sets the channel display mode to one of the four modes as described below. Press the
UP and DOWN buttons to cycle through the modes and press ENTER/MENU to confirm the
setting. The display then reverts to the base menu list.
 –The highest temperature channel is displayed. Invalid sensor inputs are ignored. If all
three sensor inputs are invalid or disabled,  will be displayed.
 –The lowest temperature channel is displayed. Invalid sensor inputs are ignored. If all
three sensor inputs are invalid or disabled,  will be displayed.
Y –The displayed channel is selected during Monitor mode with the UP and DOWN
buttons. Any sensor inputs that are invalid will display a series of dashes in place of the
temperature. Channel is the CJC and this is the only way to view it.

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Y –The active (not set to ) sensor inputs and the maximum stored peak
temperature across all channels are automatically cycled every five seconds. The displayed
channel is shown on the left digit, while the maximum is represented by an overscore
character. If all three sensor inputs are disabled,  will be displayed.
4.2.5 
This sets the 4-20 loop output parameters. There are four settings contained within this
base menu option: loop power, source, zero level, and span. Figure 4 outlines each of these
settings. The UP and DOWN buttons are used to select the desired setting, then
ENTER/MENU is used to save that setting and move to the next set. Once the final setting,
span, is set, the display reverts to the base menu.
Each of the four settings is described below in the order they are presented on the MT300:
Loop power – causes the MT300 to power the 4-20 loop internally, while  relies
on an external power source. Keep in mind that when using the  setting, the 4-20mA
loop is no longer electrically isolated.
Source –How the loop will derive its output value. will cause the loop to output the
lowest valid sensor channel. will cause the loop to output the highest valid sensor
channel. The remaining options, , , , cause the loop to output the respective
channel.
Zero –The temperature which will cause the loop to output the minimum of 4mA. The
leftmost digit will display as a hint that the setting is the zero setting.
Span –The number of degrees represented by the full range of the loop. The adjustable
range available is dependent upon the zero setting so as to prevent zero/span combinations
that could fall out of range. The leftmost digit will display as an indication that the setting
is the span setting.








5/58
...
5/8

...
(varies)
Figure 4

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4.2.6 
This setting determines the amount of time, in minutes, the Buzzer remains silenced after
SILENCE is pressed. Use UP and DOWN to adjust the value. It may also be disabled,
indicated by , which means the Buzzer will remain silenced indefinitely until another
trip occurs.
Once the desired timeout is displayed, press ENTER/MENU. The display then reverts to the
base menu.
4.2.7  through 
These nine base menu options are identical except for the channel they represent. The first
character indicates what channel the associated settings apply to, and the last character is a
sequence identifier since each channel has three identical trip settings. For example,
, , and  all contain an identical set of options for Channel 1.
The three trip settings for each channel allow different events to occur at different
temperatures - for example, engaging the Fan Relay when the temperature exceeds 100C,
Alarm Relay and Trip Relay when it exceeds 110C, and the Buzzer when it exceeds 120C.
Figure 5 illustrates the sequence of options for each trip setting. The character below each
setting, if shown, is the character that is shown on the leftmost digit on the MT300. This
character helps the user remember what each setting is, otherwise would be difficult to
distinguish from others. These characters and their meanings are given, in order of display
on the MT300, in Table 1. The two settings that do not have this are /, and
 / Y. The former determines if the sensor temperature must be higher or lower
than the setpoint, respectively, to cause a trip. The latter determines whether the CANCEL
button must be used to cancel a trip, or if a hysteresis value will cancel a trip, respectively.
When in Monitor Mode, the CANCEL button may be pressed to cancel all trips for the
currently displayed channel regardless of the  / Y setting. If the condition that
caused the trip(s) still exists, pressing CANCEL will not cancel the trip; the trip will essentially
reoccur immediately.
If the Y setting is used, a hysteresis value may be set by the user and this will allow the
MT300 to automatically cancel a trip. If is used, the trip will occur when the setpoint
is exceeded as previously explained, however the trip will now cancel itself if the sensor
temperature falls below the setpoint by the hysteresis value. For example, if the setpoint is
100C and hysteresis 10C, it automatically cancels the trip if it falls below 100C –10C = 90C.
If is used, the hysteresis operates in the opposite fashion.
EXAMPLE:
The user would like to engage the Fan Relay if Channel 1 exceeds 100C, and also engage the
Buzzer if Channel 1 exceeds 120C. Both the Fan Relay and Buzzer should disengage if
Channel 1 temperature falls below 90C.

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In addition, the Trip Relay and Alarm Relay should engage if Channel 2 falls under 0C, and do
not disengage the Trip relay unless the user cancels the trip manually.
Since the user would like to act on two different temperatures for Channel 1, two trip
settings must be set. , , and  can be used for this purpose.
It doesn’t matter which two are used, but the unused trip setting should be disabled. For
simplicity, this example will use A and B, and disable C.
For , the first option, (see Table 1), should be enabled since this trip setting will
be used. The Fan should be enabled, Setpoint set to 100,  rather than , Y
should be used rather than , and Hysteresis set to 10.
For , should be enabled since this trip setting will be used. The Buzzer should
be enabled, Setpoint set to 120,  rather than . Y should be used rather
than , and set Hysteresis set to 30.
For , should be disabled since this trip is not used.
For the Channel 2 trip,  will be used, although or could
just as well be used. and should be disabled since they aren’t used
in this example.
For , should be enabled since this trip setting will be used. The Trip Relay
should be enabled, the Alarm Relay should be enabled, Setpoint set to , and rather
than .  should be used rather than Y so Hysteresis cannot disengage the
trip, but rather will require the user to press CANCEL.
Character
Meaning

Set: Trip setting enable or disable. Setting to disable
deactivates that trip configuration, and prevents the rest of
the trip settings from appearing.

Error: Trip on sensor error.

Fan: Engage Fan relay on trip.

Alarm: Engage Alarm relay on trip.

Trip: Engage Trip Relay on trip.

Buzzer: Engage Buzzer on trip.

Setpoint: Trip setpoint.

Hysteresis: Hysteresis for automatic trip cancel.
Table 1

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
















Y

5/58
/57
...
/
5/
...
(displayed only if
previous is set to
Y)
Figure 5
4.2.8 
This configures the MODBUS serial communications. The first option sets the slave ID of the
MT300. Use UP and DOWN buttons to change the ID, and ENTER/MENU to confirm the
desired ID. The second option sets the bitrate for RS-485, or alternately, selects USB. USB
and RS-485 cannot be used simultaneously; if a bitrate is selected, that enables RS-485 for
use and disables USB.
The sequence of the settings for serial communication is shown in Figure 6.



8
96
9
8


...
7
Figure 6

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4.2.9 
This sets up the Fan Exerciser. The first setting is for the Period, which is the number of days
between Fan Relay activations. The second setting is the Duration, which is the number of
minutes the Fan Relay remains engaged. If Period is set to, the Duration will not
appear and Fan Exerciser is disabled.
The FAN LED will blink while Fan Exerciser is active.
The sequence of the settings for Fan Exerciser is shown in Figure 7.


...


...

Figure 7
4.2.10 
This sets the Manual Fan timeout. This setting is a single number that determines the
number of minutes the Manual Fan will remain engaged before automatically disengaging.
If the setting is set to, only pressing the MANUAL FAN button will disengage it.
4.2.11 
This enables or disables the Reverse Acting feature for each of the three relay outputs.
Normally, activating an output (such as when a setpoint is exceeded or when the Manual
Fan is turned on) causes the relay coil to energize and connects the “common” terminal to
the “normally open” terminal. Change the setting from to in order to
cause the respective relay to operate in the reverse fashion. The order of options presented
is shown in Figure 8. , , and represent Fan, Alarm, and Trip, respectively. Note that
this setting affects only the relays; the front panel FAN, ALARM, and TRIP indicators will
continue to behave the same.






  
Figure 8

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4.2.12 
This setting controls the brightness of the digital display. When this setting is selected by
pressing ENTER/MENU, will be displayed. Use the UP and DOWN buttons to
adjust the display brightness. Three levels are provided. When the desired brightness is set,
press ENTER/MENU. The base menu will then reappear.
It should be noted that the front and rear panel indicators are not affected. Only the 7-
segment displays can be adjusted.
4.2.13 
When this menu option is selected,  will be displayed, which is the prompt to
enter a new Primary Password. Use the UP and DOWN buttons to change the first digit to
the desired number, then press ENTER/MENU to accept and move to the next digit.
Continue until all four digits have been set.
After the last digit is set and ENTER/MENU is pressed, the menu will prompt to set the
Secondary Password if the Primary Password was set to a non-zero number. In this case,
 will be displayed and the same procedure as setting the Primary Password
should be used.
However, if the Primary Password is set to , both the Primary and the Secondary
Password will automatically be disabled; therefore the MT300 will not prompt for the
Secondary Password. See Figure 9 for the sequence of settings shown for this configuration.


...
9999

...
9999
(displayed only if
previous is set to non-
zero value)
Figure 9

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4.2.14 
This sets the behavior of the MT300 when the error occurs. When this setting
is selected by pressing ENTER/MENU, followed by the present setting is initially
displayed. The setting can be changed by pressing the UP and DOWN buttons, then
ENTER/MENU is pressed to save the setting and continue to the next setting. , , ,
and  represent Fan, Alarm, Trip, Buzzer, and Loop, respectively. The first four
settings may be set to ,  or , which turns that output off, turns that output
on, or doesn’t change that output (“no-change”), respectively. The final setting, ,
may be set to .5, .5 or ,which represents a 4-20mA loop output current of
3.5mA, 20.5mA, or no-change from its current value. See Figure 10 for the sequence of
settings shown for this configuration.
Note that these settings disregard the Reverse Acting feature. This mean that if, for
example, a relay output is set to , that relay output will be energized even if the
Reverse Acting feature is enabled for that relay.


   










.5

.5
Figure 10

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4.2.15 
This sets the behavior of the MT300 when the Test Mode is invoked. When this setting is
selected by pressing ENTER/MENU, followed by the present setting is initially displayed.
The setting can be changed by pressing the UP and DOWN buttons, then ENTER/MENU is
pressed to save the setting and continue to the next setting. , , , and represent
Fan, Alarm, Trip, Buzzer, and Loop, respectively. The first four settings may be set to ,
 or , which turns that output off, turns that output on, or doesn’t change that output
(“no-change”), respectively. The final setting, , may be set to any value between .5
and .00, or may also be set to orY. Setting a specific value will cause that
value to be applied to the MT300’s 4-20mA loop when Test Mode is invoked. If  is
selected, the 4-20mA loop’s output will not change when Test Mode is invoked, and if
Y is selected, the 4-20mA output will continuously cycle between 4mA, 12mA, and
20mA. See Figure 11 for the sequence of settings shown for this configuration.
Note that these settings disregard the Reverse Acting feature. This mean that if, for
example, a relay output is set to , that relay output will be energized even if the Reverse
Acting feature is enabled for that relay.


  











.5
.
...
Y
N
Figure 11