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Modbus Master/Slave Network Interface Module for FLEX I/O


Discontinued: No new product for sale. More Info
Recommended replacements: PLX31-EIP-MBS

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The MVI94 Modbus Master/Slave Communication Module allows Flex® processors to interface easily with other Modbus protocol compatible devices.

The module acts as an Options module between the Modbus network and the Flex backplane. Compatible devices include not only Modicon® PLCs (almost all support the Modbus protocol) but also a wide range of process and control devices from a variety of manufacturers. Many SCADA packages also support the Modbus protocol.

Features and Benefits

  • Support for the storage and transfer of up to 5000 registers to/from the Flex processor’s data files
  • User-definable module memory usage
  • Application port can emulate Modbus master or slave device
  • Supports Enron version of Modbus protocol for floating point data transactions


Slave Specifications

The MVI94-MCM accepts Modbus function code commands of 1, 2, 3, 4, 5, 6, 15 and 16 from an attached Modbus master unit. A port configured as a Modbus slave permits a remote master to interact with all data contained in the module. This data can be derived from other Modbus slave devices on the network, through a master port, or from the Flex processor.


Master Specifications

A port configured as a virtual Modbus master device on the MVI94-MCM actively issues Modbus commands to other nodes on the Modbus network. One hundred (100) commands are supported on each port. Additionally, the master port has an optimized polling characteristic that polls slaves with communication problems less frequently. The Flex processor can be programmed to control the activity on the port by actively selecting commands from the command list to execute or issuing commands directly from the ladder logic.


General Specifications

Some of the general specifications include:

  • Operation via simple ladder logic
  • Complete setup and monitoring of module through Debug port and user configuration file
  • Flex backplane interface via I/O access


FLEX I/O Interfaces



Form Factor

Single Slot 1794 Backplane compatible

Locate in any slot of Backplane

Backplane current load

20 mA @ 5 V

External power supply

12 to 24 VDC

340 to 170 mA

Operating temperature

0°C to 55°C (32°F to 131°F)

Storage temperature

-40°C to 85°C (-40°F to 185°F)


30 g operational

50 g non-operational

5 g from 10150 Hz

Relative humidity

5% to 95% (without condensation)

LED indicators

Module status

Backplane transfer status Application status

Serial activity and error LED status

Configuration Serial port (PRT1)

Mini-DIN RS-232

Hardware handshaking

Application serial Port (PRT2)


RS-232/422/485 jumper selectable 500V optical isolation from backplane

Dimensions (with Module installed in Base) H x W x D

3.7 x 3.7 x 2.7 in

94.0 x 94.0 x 69.0 mm


Ex Certificate (ATEX Directive) 106.60 kB Last Modified 11/22/2019
Declaration of Conformity (RoHS/CE) 531.03 kB Last Modified 05/18/2020
Country Approval - Russia - EAC Declaration (Wired) 1.92 MB Last Modified 01/07/2020
Korean KC Registration 373.61 kB Last Modified 03/13/2020
UL/cUL; Class 1, Div 2 1.12 MB Last Modified 02/27/2019
UL/cUL; Class 1, Div 2 (Canada) 1.14 MB Last Modified 02/27/2019