ProSoft Technology MVI56E-MCMXT User Manual

MVI56E-MCM ♦ ControlLogix Platform Reference
Modbus Communication Module User Manual
ProSoft Technology, Inc. Page 175 of 209
A server device can, however, be forced into 'Listen Only Mode' in which it will
monitor the messages on the communications system but not respond to them.
This can affect the outcome of your application program if it depends upon any
further exchange of data with the remote device. Generally, the mode is forced to
remove a malfunctioning remote device from the communications system.
Sub-function Codes Supported
Only Sub-function 00 is supported by the MVI56E-MCM module.
00 Return Query Data
The data passed in the request data field is to be returned (looped back) in the
response. The entire response message should be identical to the request.
Sub-function
Data Field (Request)
Data Field (Response)
00 00
Any
Echo Request Data
Example and State Diagram
Here is an example of a request to remote device to Return Query Data. This
uses a sub-function code of zero (00 00 hex in the two-byte field). The data to be
returned is sent in the two-byte data field (A5 37 hex).
Request
Response
Field Name
(Hex)
Field Name
(Hex)
Function
08
Function
08
Sub-function Hi
00
Sub-function Hi
00
Sub-function Lo
00
Sub-function Lo
00
Data Hi
A5
Data Hi
A5
Data Lo
37
Data Lo
27

ProSoft Technology MVI56E-MCMXT Specifications

General

Brand	ProSoft Technology
Model	MVI56E-MCMXT
Category	Control Unit
Language	English