Background To The Mtl838C; The Analog-Input Multiplexer System; Configuring The Mtl838C - Eaton MTL83*C Modbus Software Manual

Mtl fieldbus networks, pc

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Table Of Contents

Table of Contents

3 .1

The analog-input multiplexer system

The MTL838C is an analog multiplexer receiver that is used with the MTL831C

hazardous area millivolt input multiplexer transmitter. The status of up to 32 analog

inputs may be communicated from the hazardous area to the safe area via a data

highway, comprised of a simple twisted pair - over distances up to 2000m.

Each data highway must be protected by an MTL5553/5053 digital isolator when

the inputs are located in a Zone 0,1 hazardous area. The MTL831C is typically used

with thermocouple and RTD inputs and is intrinsically safe. It can be mounted in a

Zone 0,1 hazardous area and will accept 16 inputs. For systems that do not require

Zone 0 or Zone 1 installation, the MTL5553/5053 can be eliminated.

Up to two MTL831C transmitters can be combined on a single MTL838C receiver

input - up to a total of 32 analog inputs - as shown in Figure 1.

The MTL838C acts as a Modbus slave . It may be connected into any standard

Modbus network, with up to 31 MTL838C slaves on each network. If each unit has

its full complement of 32 analog inputs, the status of a total of 992 analog inputs

may be passed to a Modbus master using a single RS485 network.

3 .2

Configuring the MTL838C

The MTL838C must first be configured using software on a PC and the USB

connection. This configures things such as the slave address and communication

parameters. After the initial configuration, the MTL838C is ready to communicate

with the Modbus host. At this point, the remaining configuration may be done in

one of two ways:

Using the PC software is required for initial configuration and recommended for

first time configuration of the measuring channels.

INM MTL83xC PC Modbus Rev 1

DRAFT - 06 January 2019