Eaton MTL831C User manual

MTL831C/MTL831-PS
Analog Transmitter
September 2022
INM MTL831C Rev 7
Instruction manual
with Ex Safety Instructions (503-215 & 503-548)
MTL intrinsic safety solutions

ii INM MTL831C Rev 7
DECLARATION OF CONFORMITY
A printed version of the Declaration of Conformity has been provided separately within the original shipment of goods.
However, you can find a copy of the latest version at -
http://www.mtl-inst.com/certificates

iii INM MTL831C Rev 7
CONTENTS
DECLARATION OF CONFORMITY ......................................................ii
GENERAL SAFETY INFORMATION.................................................... iv
1 ABOUT THIS MANUAL ..............................................................1
1.1 Related documents.......................................................................1
1.2 Product description ......................................................................2
2 GETTING STARTED .................................................................2
3 COMPONENTS AND ACCESSORIES ...................................................3
4 MECHANICAL INSTALLATION.........................................................3
4.1 Location ................................................................................3
4.2 Mounting options ........................................................................3
4.2.1 Mounting on T-section DIN-rail .............................................................3
5 CONNECTIONS.....................................................................4
5.1 Address ................................................................................4
5.2 Electrical connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
5.3 Sensor inputs ...........................................................................5
5.4 RTD inputs..............................................................................5
5.5 THCs and mV inputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
5.6 THC Burnout Detection ...................................................................6
5.7 Mixed Inputs ............................................................................6
5.8 Data highway ...........................................................................6
5.9 Transmission distances ...................................................................6
5.10 IS applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
5.11 Multi-transmitter connections ..............................................................7
5.12 Cable screens .........................................................................7/8
6 ROUTINE MAINTENANCE ............................................................9
7 CONFIGURATION ...................................................................9
7.1 Sensor mode setting .....................................................................9
8 LED INDICATORS ...................................................................9
8.1 Power up ...............................................................................9
8.2 Firmware Update ........................................................................9
9 START UP AND INFREQUENT MEASUREMENTS........................................10
10 FAULT-FINDING IN THE MTL831C/MTL831C-PS ......................................10/11
11 FM, ATEX and IECEx INFORMATION ...............................................12/18
12 CCC INFORMATION .............................................................19/21
13 APPENDIX A ......................................................................22
13.1 Maintenance ...........................................................................22
13.2 Disposal ...............................................................................22

iv INM MTL831C Rev 7
GENERAL SAFETY INFORMATION
The following methods are used in this manual to alert the user to important information:-
WARNING !
Warnings are provided to ensure operator safety and MUST be followed.
CAUTION
Cautions are provided to prevent damage to the instrument.
NOTE
These are used to give general information to ensure correct operation.
SAFETY INSTRUCTIONS FOR INSTALLATION AND OPERATING PERSONNEL
The operating instructions provided here contain essential safety instructions for installation personnel and
those engaged in the operation, maintenance and servicing of the equipment.
WARNING !
Failure to comply with these instructions can endanger the lives or health of personnel and risk damage
to the plant and the environment.
WARNING !
The responsibility for planning, installation, commissioning, operation and maintenance, particularly with
respect to applications in explosion-hazard areas, lies with the plant operator.
Before commencing installation or commissioning:
• Read and understand the contents of this manual and the product datasheet
• Ensure installation and operating personnel have received adequate training for this task
• Ensure that any operating instructions are fully understood by the personnel responsible.
• Observe national and local installation and mounting regulations (e.g. IEC 60079-14).
WARNING !
If these assemblies have been used previously in general electrical installations,
they MAY NOT be used in explosion-hazard area applications.
During operation:
• Make the relevant instructions available at all times to the operating personnel.
• Observe safety instructions.
• Observe national safety and accident prevention regulations.
• Operate the equipment within its published specification.
• Servicing, maintenance work or repairs not described in this manual must not be performed without prior
agreement with the manufacturer.
• Any damage to this equipment may render its explosion protection null and void.
• No changes to any of the components that might impair their explosion protection are permitted.
If any information provided here is not clear:
• Contact Eaton’s MTL product line support or one of its representatives.
NOTE
Improper installation and operation of the enclosure can result in the invalidation of the warranty.

1INM MTL831C Rev 7
CAUTIONARY NOTE:
In common with all other electrical apparatus installed in hazardous areas,this apparatus must
only be installed, operated and maintained by competent personnel. Such personnel shall have
undergone training, which included instruction on the various types of protection and installation
practices, the relevant rules and regulations, and on the general principles of area classification.
Appropriate refresher training shall be given on a regular basis. [See clause 4.2 of EN 60079-17].
This instruction manual supplements the requirements of nationally accepted codes of practice,
for example, IEC/EN 60079-14 in Europe. All installations should comply with the relevant
sections of these codes.
In addition, particular industries or end users may have specific requirements relating to the
safety of their installations, and these requirements should also be met.
1 ABOUT THIS MANUAL
The purpose of this manual is to provide the user with information on the installation,
connection and configuration of the MTL831C/MTL831C-PS Analog Transmitter.
1.1 Related documents
This manual does NOT cover the connection or configuration of the MTL838C
receiver. For details of these items consult:
• INM MTL838C Receiver Instruction Manual
• INM MTL838C-MBT Receiver Instruction Manual
For IS installations the MTL5553 Isolator/power supply will be required. For details
of these items consult:
• INM MTL5500 range manual (MTL5553)
Other related manuals:
• EPS MTL830C Temperature Multiplexer system datasheet
• EPS MTL830C-MBT Temperature Multiplexer system datasheet
• INM MTL838C-MBF Modbus implementation manual
• INM MTL83xC LLMUX PC SW Manual- LLMUX
• INM MTL83xC Modbus PC SW Manual- Modbus
• TSN MTL838C Modbus Introduction to Modbus support notes
MTL831C
Analog Transmitter
Figure 1.1 - MTL831C Analog Transmitter

2INM MTL831C Rev 7
1.2 Product description
The MTL831C/MTL831C-PS Analog Transmitter can transfer a number of hazardous
area input signals to the safe area down a data highway consisting of a single
shielded, twisted-pair cable. It is intrinsically safe and can therefore be mounted in
Zone 0 hazardous areas or hazardous locations.
The MTL831C/MTL831C-PS can monitor up to 16 inputs from THC or millivolt
sources or 2, 3 or 4-wire RTDs or potentiometers. Multiple versions of the MTL831C/
MTL831C-PS are available to support fixed and pluggable screw terminal input
options. See the Components and Accessories section for part numbers.
A data highway is provided that can carry both signal and power over distances up to
2km, depending on the application, the cable and the (noise) environment. Shielded
twisted pair is highly recommended.
At the other end of the data highway, an MTL838C Receiver translates the
information transmitted from the MTL831C/MTL831C-PS. Multiple versions of the
MTL838C are available to support different control system interfaces. See the
Components and Accessories section for part numbers. One or two MTL831C/
MTL831C-PSs may be connected to a single MTL838C. The MTL838C provides
a *Modbus®serial data output representation of the inputs together with status
information.
When the MTL831C/MTL831C-PS transmitter is mounted in the hazardous area, the
data highway must be protected by an MTL5553 Isolator/Power Supply mounted in
the safe area.
* Modbus®is a registered trademark of Schneider Automation Inc.
2 GETTING STARTED
Installation of the MTL831C/MTL831C-PS multiplexer transmitter is divided into
three main topics.
• Mechanical Installation - how to mount the MTL831C/MTL831C-PS and how
it may be fitted into an enclosure.
• Electrical Connections - the sensor and highway connections. If units are
installed in our enclosures, it details any special wiring arrangements.
• Configuration - the address is configured with a user supplied jumper wire.
The remaining configuration is either over a Modbus® link or software on a PC.
NOTE
A new user might find it helpful to set up the system, or a simple version of it, in
an indoor test area to gain familiarisation before undertaking installation on site.

3INM MTL831C Rev 7
3 COMPONENTS AND ACCESSORIES
Product part numbers and their descriptions are listed below.
Part Number Description
MTL831C Analog Transmitter (with fixed screw terminal
inputs)
MTL831C-PS Analog Transmitter (with pluggable screw
terminal inputs)
MTL838C Receiver (Modbus/RS-485 Interface)
MTL838C-MBT Receiver (Modbus/TCP Interface)
MTL5553 Isolator/Power Supply
A standard USB Type C cable (not supplied by Eaton) is required to configure
the MTL838C
4 MECHANICAL INSTALLATION
4.1 Location
The MTL831C/MTL831C-PS can be installed in either safe or hazardous areas
(including Zone 0) depending upon the requirements of the application.
4.2 Mounting options
The MTL831C/MTL831C-PS must be mounted on a vertical plane on vertical
or horizontal DIN rail to meet accuracy specifications. Heat sources causing a
temperature gradient in the MTL831C/MTL831C-PS may cause accuracy outside
of specifications. The unit can be mounted on T-section DIN-rail. Eaton has a range
of enclosures- ENC8, ENC8-SS, ENC83 or ENC83-SS- to provide suitable IP67
protection if the transmitter is located in an exposed area.
4.2.1 Mounting on T-section DIN-rail
To install, tilt the MTL831C/MTL831C-PS to the left and hook to the left side of the
standard 35mm DIN46277 T-section rail. Push to the right and allow the unit to rotate
down to sit flat on the DIN Rail. Allow it to spring back to the left and the right side
will hook to the DIN Rail.
To remove, push the MTL831C/MTL831C-PS to the right and tilt the right side away
from the DIN Rail. While tilted, allow it to spring back to the left and remove from
the DIN Rail.
1Remove
Install
Push 2

4INM MTL831C Rev 7
5 CONNECTIONS
The connection terminals are along the edges of the Analog Transmitter. These are
divided into input sensor terminals (1 to 16), the Address terminals (A, S), and the
data highway terminals (+, S,-), as shown below.
5.1 Address
Leaving these two pins (A, S) open, sets the address of the MTL831C/MTL831C-
PS to “1”. A jumper on these two pins sets the address to “2”. Either is valid for a
system with only one MTL831C/MTL831C-PS connected to the MTL838C. When
two MTL831C/MTL831C-PSs are connected to a single MTL838C, they must be
addressed uniquely. If they are on the same address, only one will communicate
with the MTL838C. The address affects where the data is seen in the PC Software
and what is available on the RS485 ports:
ADDRESS PC Software Modbus Port A or B LLMUX Emulation
1 MTL831C #1 tab Channels 1-16 Link 1, channels 1-16
2 MTL831C #2 tab Channels 17-32 Link 2, channels 1-16

5INM MTL831C Rev 7
5.2 Electrical connections
The data highway connector is pluggable (with securing screws) and has standard
screw-terminals for connecting wiring. The MTL831C-PS sensor ports use pluggable
connectors without securing screws. Cables for pluggable connectors without
securing screws are to be secured and supported
Type Conductor size
Pluggable screw terminals 0.14 to 2.5mm2
Fixed screw terminals 0.14 to 1.4mm2
NOTE
A torque screwdriver set between 0.5 - 0.6Nm is recommended for tightening all
terminal screws.
Screw Terminal
5.3 Sensor inputs
Sensors connected to the MTL831C/MTL831C-PS should not be earthed. This
avoids differences in earth potential that could affect measurement accuracy or
damage the MTL831C/MTL831C-PS. If sensors must be earthed they should be
located close to each other to avoid differences in earth potential.
5.4 RTD inputs
The 16 channels can be configured for 2, 3 or 4 wire mode as shown in the
connection diagram on the unit overlay. Software configuration is also required to
select the proper measuring method. This is done via PC Software or Modbus. By
default the MTL831C/MTL831C-PS is configured for mV inputs.
5.5 THCs and mV inputs
Connect up to 16 THC or mV inputs directly to the input terminals as shown on the
overlay connection diagram making sure the polarity is correct.
A
DATA
HIGHWAY
S
MTL831C
Analog Transmitter
mtl-inst.com
S
-
+
R
1
2
3
4
5
6
7
15
16
14
13
12
10
11
9
8
ABC D
RTD
TC & mV
ADDRESS
DCBADCBADCBA
DCBADCBA
DCBADCBA
DCBADCBA
DCBADCBA
DCBADCBA
DCBADCBADCBA
POWER
ERROR
Push
Remove
Install
1
2

6INM MTL831C Rev 7
5.6 THC Burnout Detection
The MTL838C/MTL831C/MTL831C-PS system provides for thermocouple burnout
detection. This is implemented by periodically measuring the resistance of the
thermocouple and comparing it to the initial measurement. If the resistance
increases by more than 50 ohms, a warning is available in the sensor status (readings
are still available). For more information, see the instructions for the MTL838C
Receiver. The following are events that lock in the initial resistance measurement:
• The MTL831C/MTL831C-PSis powered up (initial resistance measurement is
locked in after 30 seconds).
• A Channel configured as a THC goes open for at least 1.3 second and then
closed (this is intended to reset the initial value when the THC is replaced).
• A Channel that was not configured as a THC is changed to a THC. This
configuration change would come from the PC software or Modbus.
5.7 Mixed Inputs
It is possible to mix any combination of different input sensor types on the 16
input channels.
Connect the different sensors appropriately, as shown in the connection diagram on
the unit overlay.
5.8 Data highway
The data highway connection is also the source of DC power for the MTL831C/
MTL831C-PS. It is important that the polarity of the wiring on the “+” and “-“
terminals is correct. A shielded twisted-pair wire is recommended. The “S” terminal
is wired to the cable shield. It is not internally connected in the MTL831C/MTL831C-
PS.
5.9 Transmission distances
The maximum data highway length will depend upon two key factors: the type
and quality of the cable used, and the level of electrical interference present in the
environment.
Typically a user might expect: IS applications- 1km
Non-IS applications- 2km.
The reduced distance for IS applications is due to the voltage drop from the current
limiting resistor in the MTL5553 IS isolator and may also be limited by the inductance
and capacitance of the data highway cable that is required for the IS cable parameter
calculations. (See IEC/EN 60079-14 for further details).
We recommend using 16 gauge Foundation Fieldbus cable that has been
checkmarked as meeting the FF standard for data highway cables. This will help
ensure that the maximum lengths can be achieved with successful communication
in the presence of noise.
Also, do not run the data highway cable near or in parallel with high voltage lines,
VFDs, or motors driven with a VFD as these can create noise that would interfere
with communication.

7INM MTL831C Rev 7
5.10 IS applications
For IS applications, the data highway connection must be via a galvanic isolator and
so an MTL5553 isolator is connected in-line in the safe area (see ATEX and IECEx
Information section.).
The - and + terminals of the data highway should be connected to the corresponding
–ve and +ve terminals of the MTL5553 (13 & 14 respectively) located in the safe area.
See the section on ATEX and IECEx information for detailed instructions.
NOTE
A built-in terminator is activated by installing a jumper between terminals 7 and 8
of the MTL5553. Do not install a jumper across terminals 7 and 8. The MTL5553
terminator is not used in the MTL830C system installation. Activating the
terminator may cause MTL830C system data highway communications to fail.
5.11 Multi-transmitter connections
Connect the data highway to a receiver for MTL831C/MTL831C-PS Transmitter
#1 as in diagram below. Connect the MTL831C/MTL831C-PS Transmitter #1 data
highway (+, S, and – terminal) to the equivalent terminals on a MTL831C/MTL831C-
PS Transmitter #2. Install a jumper wire between the Address terminals (A and S) on
MTL831C/MTL831C-PS Transmitter #2.
NOTE
The MTL831C/MTL831C-PS is supplied with a double sided data highway
connector to facilitate linking two MTL831C/MTL831C-PS Transmitters.
Up to two MTL831C/MTL831C-PS Analog Transmitters may be connected on a single
data highway to the MTL838C/MTL5553.
5.12 Cable screens
Each cable screen should be earthed in only one location.
5.12.1 Sensor screens
Generally, screens of sensor cables are tied to earth using an earth bar tied to local
instrument earth in the MTL831C/MTL831C-PS enclosure. If a sensor cable screen is
earthed at the sensor, then it should not be earthed or connected to other screens at
the MTL831C/MTL831C-PS.
Transmitter #1
Transmitter #2
To Receiver
DATA Highway

8INM MTL831C Rev 7
5.12.2 Data Highway screen with an MTL5553
Hazardous area installation of the sensors or MTL831C/MTL831C-PS require the use
of an isolator/power supply such as the MTL5553.
The screen of a Data Highway cable between the MTL831C/MTL831C-PS transmitter
and MTL5553 isolator is earthed to a local instrument earth in the MTL831C/MTL831C-
PS’s field enclosure or the at the MTL5553’s enclosure.
The screen of a Data Highway cable between the MTL5553 isolator and the MTL838C
is tied to the “S” terminal of the Data Highway port on the MTL838C. The “S” terminal
is internally connected to the GROUND terminals of the MTL838C. The GROUND
terminals of the MTL838C must be earthed at a local instrument earth.
Figure 1 - Recommended Screen Earthing for MTL830C System when Using an
MTL5553 Isolator
5.12.3 Data Highway screen with no MTL5553
The screen of a Data Highway cable between the MTL831C/MTL831C-PS transmitter
and the MTL838C is tied to the “S” terminal of the Data Highway port on the MTL838C.
The “S” terminal is internally connected to the GROUND terminals of the MTL838C.
The GROUND terminals of the MTL838C must be earthed at a local instrument earth.
Figure 2 - Recommended Screen Earthing for MTL830C System when using an
MTL5553 Isolator
+
S
-
+
S
-
+
S
-
+
S
-
Optional
Second
MTL831C[-xx]
Analog
Transmitter
MTL838C[-xxx]
Data Highway
terminals
GROUND
terminals
+
S
-
Data
Highway
Local
Instrument
Earth
Internal connection
between Data
Highway Screen
terminal and
GROUND terminals
MTL831C[-xx] Analog
Transmitter
A B C D
CH 1
AB C D
CH 16
Sensor
Local
Instrument
Earth
Earth
Bar
Sensor
Screen
(Shield)
…...
+
-
+
S
-
+
S
-
+
S
-
+
S
-
Optional
Second
MTL831C[-xx]
Analog
Transmitter
MTL5553
Isolator/Power
Supply MTL838C[-xxx]
Data Highway
terminals
GROUND
terminals
+
-
+
S
-
Data
Highway
Local
Instrument
Earth
Internal connection
between Data
Highway Screen
terminal and
GROUND terminals
Local
Instrument
Earth
MTL831C[-xx] Analog
Transmitter
A B C D
CH 1
A B C D
CH 16
Sensor
Local
Instrument
Earth
Earth
Bar
Sensor
Screen
(Shield)
…...

9INM MTL831C Rev 7
6 ROUTINE MAINTENANCE
Check the general condition of the installation periodically to make sure that no
deterioration has occurred. At least every twoyears (and more frequently for particularly
harsh environments) check that:
• cable, wire connections, terminations, and screens are in good condition
• the green POWER LED is blinking
• the red ERROR LED is not lit
• no signs of damage or corrosion are present
WARNING !
The plastic parts can store static charge. Clean only with a damp cloth
to prevent static buildup.
7 CONFIGURATION
The only hardware configuration is the setting of the unit’s address – see section 4.1.
The remaining configuration comes from the MTL838C.
7.1 Sensor configuration
All sensor configurations are done through the MTL838C PC software or via
Modbus. Note that the configuration data is actually held in the MTL838C for one or
two MTL831C/MTL831C-PS Transmitters – depending on how many are connected.
If an MTL831C/MTL831C-PS must be replaced for some reason, its configuration
is automatically transmitted from the MTL838C to the MTL831C/MTL831C-PS
when it is powered up. See the PC software or Modbus manuals for information on
configuring sensors.
8 LED INDICATORS
There are 2 LEDs to indicate the health and status of the unit. The following are their
meanings:
POWER: When illuminated (green), this indicates that power is
available to the unit. When it blinks it means that at least
one good packet was received from the MTL838C in the last 1/4sec.
This LED should normally be blinking.
ERROR: Red illumination means that there was a CRC error in a packet
received from the MTL838C. This LED goes off after 1/4sec without
an error. The more it is on the more errored packets are
being received.
8.1 Power up
When the unit first powers up, both LEDs come on for about 1 second and then go off.
The POWER LED should then come back on. It is normal for the red LED to blink once
or twice during the first 10 seconds or so after applying power.
8.2 Firmware Update
During the first phase of the Firmware update which is initiated from the PC
software, the POWER and ERROR LEDs alternately blink. When the first processor
is updated, the unit restarts. During the remaining update process for the other two
processors, the POWER LED either blinks normally or is on steady while the internal
update process is taking place. The PC software provides status information during
the update process.

10 INM MTL831C Rev 7
9 START UP AND INFREQUENT MEASUREMENTS
The MTL831C/MTL831C-PS enters a startup process after power is applied. Normal
operation begins about 60 seconds after power is applied. Thermocouple resistances
(for burnout detection) and CJC (Cold Junction Compensation) temperatures are
being measured frequently during startup. Afterwards these measurements are
made infrequently (on the order of minutes). See section 4.5 for information on
Thermocouple Burnout Detection.
10 FAULT-FINDING IN THE MTL831C/MTL831C-PS
The following are some tips when the system does not seem to be functioning
correctly. If you are still unable to solve the issue, please contact Eaton Technical
Support for help.
The POWER light is not ON or blinking
• There is not adequate power for the unit to function. Using a Voltmeter,
measure the voltage at the data highway “+” and “-“ terminals and verify
that it meets the minimum voltage specification. A margin of at least 1 volt
over the minimum is recommended.
• The unit is faulty. Please contact Eaton for further assistance.
The COMM light comes on and does not blink
• Two MTL831C/MTL831C-PSs are at the same address. If there is more than
one MTL831C/MTL831C-PS (there should never be more than 2), one and
only one of them should have a jumper wire between the two ADDRESS
pins (A, S). When two MTL831C/MTL831C-PSs are at the same address
whichever one powers up first will be communicating with the MTL838C.
The other unit recognizes its address already being used and remains idle.
• No communication signal is getting to the MTL831C/MTL831C-PS. There can
be multiple reasons for this:
• In an IS installation, power for the MTL831C/MTL831C-PS is coming from
the MTL5553.
If the MTL838C is not powered or not connected properly no signal will
get to the MTL5553 to be passed to the MTL831C/MTL831C-PS is.
• For non-IS installations, power comes from the MTL838C, so it is
possible the MTL838C has stopped communicating. Investigate by
connecting to the MTL838C with a USB cable, PC, and the PC Software.
It may be necessary to repower the MTL838C.
• The MTL831C/MTL831C-PS has stopped receiving communication. Try
disconnecting it and reconnecting it to reboot it. The data highway cable
is too noisy for the MTL831C/MTL831C-PS to communicate with the
MTL838C. Inspect the data highway cable run and make sure it is not
near power cables, VFDs, VFD controllers, or other high current noise
producing cables and equipment.
• The unit is faulty. Please contact Eaton for further assistance.
The ERROR light comes on periodically
• The light flashes regularly every one or two seconds. If this persists,
you may see the unit reboot – see section 6.1. Power cycle the unit by
disconnecting and reconnecting the data highway cable if this happens
and keeps recurring. The failure of a firmware update process which would
have been initiated from the PC software could also cause this. The
solution would be to try the firmware update process again. If that fails to
remedy the issue, the unit could be faulty. Contact Eaton for assistance.
• The light flashes randomly or often. This is likely a CRC error on packet
receipt (bad packet). The following are the potential causes:

11 INM MTL831C Rev 7
• Extreme noise source is affecting the data highway cable. This could
include VFDs, welders, etc.
• Check all wiring terminations to see that they are tight and there are no
unintended shorts.
• Verify that the data highway shield is earthed at one location only.
• Verify the integrity of the data highway cable.
• Use the PC software to check the diagnostic information.
• Try rebooting each device connected to the data highway one at a time.
• Contact Eaton for assistance if the source of the issue cannot be found.
The POWER and ERROR lights alternately turn on and off
• This is an indication that the unit is being updated with new firmware. If
a firmware update fails to complete properly, the unit can get stuck in this
mode. Perform the firmware update again. If this does not fix the issue,
contact Eaton for assistance.

12 INM MTL831C Rev 7
11 FM, ATEX, and IECEx Information

13 INM MTL831C Rev 7

14 INM MTL831C Rev 7

15 INM MTL831C Rev 7

16 INM MTL831C Rev 7