ProSoft Technology MVI56E-MNETR - Manual (Page 127)

Reference MVI56E-MNETR ♦ ControlLogix Platform
User Manual Modbus TCP/IP Interface Module with Reduced Data Block
ProSoft Technology, Inc.
Page 127 of 153
August 31, 2009
Request
Function code 1 Byte 0x08
Sub-function 2 Bytes
Data N x 2 Bytes
Response
Function code 1 Byte 0x08
Sub-function 2 Bytes
Data N x 2 Bytes
Error
Error code 1 Byte 0x88
Exception code 1 Byte 01 or 03 or 04
Sub-function codes supported
Only Sub-function 00 is supported by the MVI56E-MNETR 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