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MVI71-Serial Picture

Modbus Master/Slave Network Interface Module for PLC


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The MVI71 Modbus Master/Slave Network Interface Module allows Rockwell Automation PLC processors to interface with Modbus-compatible devices. Compatible devices include not only Modicon PLCs but also a wide assortment of third-party devices found in nearly every industry.

Features and Benefits

The inRAx Modbus Master/Slave Communication Module is designed to allow PLC processors to interface easily with Modbus protocol-compatible devices and hosts.

The MVI71-MCM module acts as an input/output module between the Modbus network and the Rockwell Automation backplane. The data transfer from the PLC processor is asynchronous from the actions on the Modbus network. A 5000-word register space in the module exchanges data between the processor and the Modbus network.

Many host SCADA packages support the Modbus protocol, while devices commonly supporting the protocol include several PLCs, as well as many other third party devices in the marketplace. (For a partial list of devices that speak Modbus, please visit the ProSoft Tested section of the ProSoft Technology web site).


Applications using the Modbus Communication Module can be found in many industrial sectors and in the following applications

  • Foreign device data concentrator
  • Pipelines and offshore platforms
  • Food processing
  • Mining
  • Pulp and paper
  • SCADA communications


  •  Single Slot - 1771 backplane compatible
  • The module is recognized as an Input/Output module and has access to processor memory for data transfer between processor and module
  • Ladder Logic is used for data transfer between module and processor.
  • Configuration data obtained through user-defined ladder. Sample ladder file included




Form Factor

Single Slot 1771 chassis compatible
BTR/BTW data transfer
Local or remote rack

Backplane current load

800 mA @ 5 VDC

Operating temperature

32° F to 140° F (0° C to 60° C)

Storage temperature

-40° F to 185° F (-40° C to 85° C)


30 g operational
50 g non-operational


5 g from 10 to 150 Hz

Relative humidity

5% to 95% (without condensation)

LED Indicators

Module status
Backplane transfer status
Application status
Serial activity and error LED status

Debug/Configuration port (CFG)

CFG Port (P1)

RJ45 (DB-9M with supplied cable)
RS-232 only

Configuration Connector

RJ45 RS‑232 Connector (RJ45 to DB-9 cable shipped with unit)

Application Ports

Application Serial port (Serial Modules)

Two RJ45 RS-232/422/485 Application ports


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