Replacing an MTL830B System with an MTL830C System connected to a Honeywell LLMUX card

1 Introduction

This document provides instructions for replacing an MTL830B temperature multiplexer system with an MTL830C temperature multiplexer system. A block diagram showing an example hardware installation before and after installation is shown below for reference.

2 Steps for replacing the MTL830B with the MTL830C system

1. Record the settings of the existing MTL830B system.
   1. Record the channel configuration (thermocouple, mV, 2-wire RTD, 3-wire RTD, or 4-wire RTD).
   2. Record the address of each MTL831B. The address is set by the positions of SW 100 switches 1 and 2. Note: Only addresses 1 and 2 are used.

   Switch Settings for Address:

   Diagram shows switch positions for SW 100 (side view) with ON and OFF states, corresponding to Tx Address 1, 2, 3, 4.

   SW 100 SW 101 - Tx address mapping:

   Table shows switch combinations for SW 100 and SW 101 mapping to Tx # (1, 2, 3, 4).

2. Power off the MTL830B system by turning off or disconnecting the power to the MTL838B-HON units.
3. Replace each MTL831B with an MTL831C (refer to the MTL831C Analog Transmitter Instruction Manual for details).
   1. For hazardous area installations, confirm the Intrinsic Safety entity parameters of the sensors are compatible with the entity parameters of the MTL831C.
   2. Move the wires from each MTL831B sensor input channel to the corresponding MTL831C sensor input channel.
   3. Each MTL 831C sensor input channel has 4 terminals labelled A, B, C, and D. The proper connections to the terminals for each input type are shown in the drawing below.

   Figure 2: MTL 831C Terminal Connections for the Various Sensor Types

   Diagram shows terminal connections for TC & mV inputs (terminals A, B, C, D) and RTD inputs (terminals A, B, C, D) on the MTL 831C.

   4. The MTL831C supports direct connection of 2, 3, and 4-wire RTDs, eliminating the extra components, terminal strips, and wiring used with the MTL831B. Connect each RTD to its own input channel port.
   5. Move the Data Highway cable from the MTL831B to the MTL831C. If two Data Highway cables were used with the MTL830B system, select one of the two cables to use with the MTL830C system. The second Data Highway cable is not connected.
   6. On the MTL831C replacing the MTL831B with address 2 (if present), install a jumper wire between the ADDRESS terminals A and S (terminal numbers 7 and 8).

   Figure 3: Jumper Wire Between Address Terminals

   Diagram shows a jumper wire connecting terminals 7 and 8 (labeled A and S) on an MTL831C unit.

4. If an MTL3052 Isolator is installed in the Data Highway cable, replace it with the MTL5553 Isolator/Power Supply (refer to the MTL5500 Series Instruction Manual for details).
5. Replace the MTL838B-HON with the MTL838C (refer to the MTL838C Receiver Instruction Manual for details).
   1. Move the MTL838B-HON RS-485 ports to the corresponding terminals of the MTL838C.
   2. Move the wires from the MTL838B-HON Data Highway port to the corresponding terminals of the MTL838C. If two Data Highway cables were used with the MTL830B system, connect the same cable attached to the MTL831C Data Highway port(s) to the MTL838C Data Highway port. The second Data Highway is not connected.
   3. Move the wires from the MTL838B-HON power port to the corresponding terminals of the MTL838C.
6. Apply DC power to the MTL830C system (turn on power to the MTL838C and MTL5553, if installed).
7. Verify the MTL838C green POWER LED turns on.
8. Verify the MTL838C green COMM LED is flashing. This indicates communication is established with the MTL831C(s). If not, verify proper connection of the Data Highway wiring.
9. Install the MTL83xC Configurator software on a computer.
10. Connect the computer to the MTL838C USB-C port.
11. Use the software to configure the MTL838C to match the old MTL830B system settings you recorded (refer to the MTL83xC LLMUX Emulation manual for details). On the MTL838C tab:
    1. Check for relevant firmware updates for the MTL831/MTL838C.
    2. Select LLMux as the Communication Protocol.
    3. Select the MTL831C transmitters that are connected (#1, #2, or both).
    4. Select the type of inputs connected to each MTL831C (mV/TC or RTD).
    5. Select the Line Frequency to 60Hz or 50Hz (frequency of power on site).
    6. Click the Download -> MTL838C button.

    Figure 4: Example MTL838C Configuration

    The MTL83xC Configurator interface is shown, with tabs for MTL838C and MTL831C. Fields include General Configuration, Communication Protocol, Tag Name, Transmitters Connected, LLMux Types, Line Frequency, and Alarm settings. Connection status (Transmitting, Receiving) and action buttons (Reset Configs, Download, Sign Off, Upload) are also visible.

12. Use the software to configure the MTL831C(s) to match the old MTL830B system settings you recorded.
    1. Note: The Honeywell system sends most of the channel configuration to the MTL830C system. However, the number of wires used for RTDs is not included in the configuration data sent by the Honeywell system. The default channel configuration for RTDs is 3-wire. If mV, thermocouple, and 3-wire RTD are the only channel configurations used, then no MTL831C configuration is required. If any channels are connected to 2- or 4-wire RTDs, set those channels using the software as described below.
    2. On each MTL831C tab where MTL831C is configured to measure RTDs, select the correct number of wires for the RTD for each channel. Note: This is only required for channels connected to 2- or 4-wire RTDs. Any channels connected to RTDs and left as “Not Configured” will be treated as 3-wire RTD when the Honeywell system enables them.
    3. Click the Download -> MTL831C button.
    4. Note: The MTL838C remembers the last way a channel was configured for RTD even if it is later unconfigured. If the Honeywell system then configures the channel for RTD, it will use the number of wires that was last configured by the software. If you see unexpected behavior with RTDs, use the software to configure the number of wires on ALL RTD channels so that you know they are correctly configured.

    MTL83xC Configurator - MTL831C Configuration Table:

    The configurator shows a table with columns for Channel, Input Type, Safety, Drive, High Alarm, Low Alarm, Input Zero, Output Zero, Gain, and Reading. Example entries include '4W RTD Ω', '3W RTD Ω', '2W RTD Ω' with associated settings.

13. Disconnect the computer from the MTL838C. Note: The Honeywell system will not be able to communicate with the MTL830C system while the computer is connected to the MTL838C.
14. Confirm the new system is operating properly using the Honeywell system.

3 Frequently Asked Questions

• Is the Data Highway cable between the transmitter and receiver required to be Fieldbus cable? No. Standard, twisted-pair instrumentation cable may be used.
• Is there a separate Honeywell version of the receiver, equivalent to MTL838B-HON? No. The MTL838C receiver is configurable for either standard (Modbus) or Honeywell (LLMUX) use.
• Can the MTL830C transmitter and receiver be used without the MTL5553 isolator, in non-IS applications? Yes. The isolator is only required for hazardous area applications.
• In Modbus applications, are changes needed to be programming of the Modbus master if an MTL838B is replaced by an MTL838C? No. The Modbus mapping of the MTL838C is exactly the same as the MTL838B.

Company Information

Eaton Electric Limited, Great Marlings, Butterfield, Luton Beds, LU2 8DL, UK.

Tel: +44 (0)1582 723633 | Fax: +44 (0)1582 422283

E-mail: mtlenquiry@eaton.com | www.mtl-inst.com

© 2019 Eaton. All Rights Reserved.

Publication No. TSN MTL830x Transition Rev 1 110719