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New VersaMax®  Modular Modbus Master Module

New VersaMax® Modular Modbus Master Module

Product News Friday, April 28, 2006: CIMTEC Automation

New VersaMax Modular Genius NIU Modbus Master Module

The VersaMax Serial Communications Module, IC200CMM020, operates as a Modbus RTU Master in a VersaMax I/O Station controlled by a Genius Network Interface Unit. The serial Communications Module may be installed at any location in the I/O Station. Up to two Serial Communications modules can be used per I/O Station. This new module allows the user to easily connect to Modbus Slave devices remotely such as Variable Frequency Drives, Bar Code Readers, displays and much more.

Product Overview
Modbus RTU Communications
The VersaMax Serial Communications module supports Modbus RTU Master protocol. To operate as a Master, the Serial Communications module must receive commands from a remote host. For example, the remote host could be an RX7i PLC that communicates with the I/O Station’s VersaMax Genius NIU via a Genius Bus Controller module.

Commands from a Remote Host
The Serial Communications module exchanges commands with the remote host via the input and output memory areas of the I/O Station’s Genius NIU. The commands used for these communications are referred to as "memory mapped COMMREQs" because their format is similar to the existing GE Fanuc Modbus RTU COMMREQ (Communication Request) commands. These commands are defined in the document Modbus RTU Communications, GFK-2220C or later.

Commands from the remote host to the module are sent via %AQ memory. The module returns the command response in the first two %AI registers that have been configured for the module.

The Serial Communications module supports RTU Master command numbers 65520, 8000, 8001, 8002, and 8003 as described in the Modbus RTU Communications Manual, GFK-2220.

Compatibility: The Modbus Serial Master module is compatible with the VersaMax Genius NIU (IC200GBI001) only, no other VersaMax NIUs or VersaMax CPUs are supported at this time.

Flexibility: The Modbus Serial Master module is ideal for interfacing with a variety of third party Modbus Slave devices. The Genius NIU can easily be connected to any PAC or Series 90 controller.

Typical Applications

  • Water/Waste Water
    • Pumping stations
    • Lift stations
  • Transportation
    • Traffic control
    • Ventilation systems
  • Any application that has third party slave devices such as Variable Frequency Drives, marques, displays, controllers and other devices that communicate over Modbus serial.

Customer CTQs
  • Remote interface to Modbus Serial devices over a Genius LAN
  • Simple interface support to PAC controllers
  • Support redundant LANs
Serial Modbus Master Module
Number of Serial Communications Modules Up to 2 per Genius NIU I/O Station
Number of RTU slaves per Serial Communications Module 1 to 247
Serial Port Type

RS-485. 15-pin subminiature ‘D’ connector.
For RS-232 communications, an RS-485 to RS-232 adapter such as IC690ACC901 can be used. Adapter IC690ACC901 can be installed with its right-angle cable hanging down.
RS-485 supports both 2-wire and 4-wire electrical interfaces

Baud Rate Supported 1200, 2400, 4800, 9600, and 19200, and half or full duplex operation
COMMREQ command memory (%AQ) required in the GENERIC_COMM module hardware configuration Depends on individual COMMREQ content.
Minimum: 22 words
Maximum: 64 words
COMMREQ response memory (%AI) required Minimum: 2 words
Maximum: 64 words for Genius NIU
RTU Master Commands

As described in Modbus RTU Communications Manual, GFK-2220. Minor differences as described below.
65520, Initialize RTU Master Port
8000, Clear RTU Master Dig. Status
8001, Read RTU Master Dig. Status
8002, Send RTU Read/Force/Preset Query
8003, Send RTU Diagnostic Query

VersaMax Micro 64 Ordering Information
Part number
Description Open for orders
IC200CMM020 VersaMax Modbus Master Serial Communications Module NOW

Firmware and Software Requirements
No new firmware required on Genius NIU or CPU.

GFK Description
GFK-2423 VersaMax Serial Communications ModuleVersaMax Micro 64 Data Sheet

For more information, please contact:

Bill Black
Controllers Product Manager
Phone: (434) 978-5362
Fax: (434) 978-5205

Product Categories:

Instrumentation & Control » PLC, MMI and DCS » VersaMax Modular Modbus Master Module