MTL838C Temperature Multiplexer System
Product Information:
The MTL838C is a device designed by Eaton to support Honeywell
LLMUX according to Honeywell LLMUX specifications. It provides easy
configuration options for the MTL838C and allows for the connection
of MTL831Cs.
Product Usage Instructions:
- The default mode for the MTL838C is Modbus mode.
- To switch the MTL838C to LLMUX mode, follow these steps:
- Use the PC software provided.
- Locate the dropdown box and select “LLMUX mode”.
- Use the PC software provided.
- Select the number of MTL831Cs connected to the MTL838C.
- By default, both MTL831Cs are enabled.
MTL838C:
- By default, the input type is set to “mV/THC”.
- For RTD (Resistance Temperature Detector) input type, use the
PC software to configure the channels. - The PC software allows you to change the number of wires for
RTD types on a channel-by-channel basis.
| Index | Description | HW Codes |
|---|---|---|
| 0 | Not Configured (default) | De-configure command 0x0C, 0x7E, 0x7F |
| 1-11 | Voltage (mV), 2W RTD, 3W RTD, 4W RTD, TC, B, mV, CJC, TC, E, mV, CJC, TC, J, mV, CJC, TC, K, mV, CJC, TC, R, mV, CJC, TC, S, mV, CJC, TC, T, mV, CJC | HW Codes as provided |
NOTES:
- The “Not Configured” mode is implemented as “mV” in the MTL831s
as they always have to be doing something. - The HW system does not ask the LLMUX to return the channel
configuration code, so multiple codes that make the same
measurement can be represented by one input type.
Eaton Electric Limited, Great Marlings, Butterfield, Luton Beds,
LU2 8DL, UK. Tel: + 44 (0)1582 723633 Fax: + 44 (0)1582 422283
E-mail: [email protected] www.mtl-inst.com
DRAFT 14 March 2017
Technical support note MTL intrinsic safety solutions
July 2019 TSN838C LLMUX Rev 2
Supporting the LLMUX with the MTL838C
Eaton has designed the MTL838C according to Honeywell LLMUX spec. To support Honeywell LLMUX with the existing installation, we propose the below workaround for easy configuration of the MTL838C.
1. The out-of-box default for the MTL838C will be Modbus mode. The following would need to be done for each MTL838C using the PC Software:
a. The HW user will need to switch the MTL838C to LLMUX mode (a single dropdown box). b. They will then need to configure the number of 831Cs connected to the 838C.
By default both are enabled. c. Finally select the input type for each MTL831 connected to the MTL838C.
mV/THC is the default but RTD may be selected instead.
2. The MTL838C will interpret the Configuration codes from the HW system exactly as documented previously for the MTL838B EXCEPT that all RTDs will be assumed to be 3-wire type.
3. If the HW user wants to use a 2-wire or 4-wire RTD, they will have to use the PC software to configure the channels. The PC Software is the only way to change the number of wires for RTD types. This is selectable on a channel by channel basis.
The PC configuration options will be:
Index 0 1 2 3 4 5 6 7 8 9 10 11
Description Not Configured (default) Voltage (mV) 2W RTD 3W RTD 4W RTD TC, B, mV, CJC TC, E, mV, CJC TC, J, mV, CJC TC, K, mV, CJC TC, R, mV, CJC TC, S, mV, CJC TC, T, mV, CJC
HW Codes De-configure command 0x0C, 0x7E, 0x7F 0x08, 0x09, 0x0A, 0x0B 0x08, 0x09, 0x0A, 0x0B 0x08, 0x09, 0x0A, 0x0B 0x04 0x02 0x00 0x01 0x06 0x05 0x03
NOTES
1. The Not Configured mode would be implemented as mV in the 831s as they always have to be doing something.
2. The HW system does not ask the LLMUX to return the channel configuration code so multiple codes (that make the same measurement) can be represented
by one input type.
Eaton Electric Limited, Great Marlings, Butterfield, Luton Beds, LU2 8DL, UK. Tel: + 44 (0)1582 723633 Fax: + 44 (0)1582 422283 E-mail: [email protected] www.mtl-inst.com
© 2018 Eaton All Rights Reserved Publication No. TSN838C LLMUX Rev1 020718 July 2018
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Safety | Analysis and testing | Protection | Warning | Eaton
