ProSoft Technology MVI56E-MCMR - Manual (Page 55)

MVI56E-MCMR ♦ ControlLogix Platform Configuring the MVI56E-MCMR Module
Modbus Communication Module with Reduced Data Block User Manual
ProSoft Technology, Inc. Page 55 of 225
May 13, 2014
2.3 Configuration as a Modbus Master
2.3.1 Overview
This section describes how to configure the module as a M ODBUS M ASTER
device. The Master is the only device on a Modbus network that can initiate
communications. A Master device issues a request message, and then waits for
the slave to respond. When the slave responds, or when a timeout has occurred,
the Modbus Master will then execute the next command in the list.
The following ProSoft Configuration Builder sections contain the Modbus Master
configuration. You must configure all three sections.
1 The B ACKPLANE C ONFIGURATION section sets up the backplane
communication between the MVI56E-MCMR module and the ControlLogix
processor (page 56). These settings include register addresses for ReadData
and WriteData. You can configure up to 5000 data registers in the module to
exchange data with the ControlLogix processor.
2 The M ODBUS P ORT 1 and M ODBUS P ORT 2 sections configure the Modbus
application serial ports (page 57). These sections configure parameters such
as baud rate, parity, data bits, stop bits, and command response timeout.
3 The M ODBUS P ORT 1 C OMMANDS and M ODBUS P ORT 2 C OMMANDS sections
define a polling table (command list) for the Modbus Master (page 60). These
sections contain the addresses for devices on the network, the types of data
(Modbus Function Codes) to read from and write to those devices, and the
location to store the data within the m
odule’s 5000 data registers.