ProSoft Technology MVI56E-MNET/MNETXT - Manual (Page 128)

Reference MVI56E-MNET / MNETXT ♦ ControlLogix Platform
User Manual Modbus TCP/IP Interface Module
Page 128 of 181 ProSoft Technology, Inc.
April 23, 2014
Unformatted Pass-Through Blocks
When the unformatted pass-through mode (code 1) is selected, information is
passed from the module to the processor with a block identification code of 9996.
Word 2 of this block contains the length of the message, and the message starts
at word 3. Other controller tags are required to store the controlled values
contained in these messages.
Pass-Through Block 9996 from Module to Processor
Word Offset Description Length
0 0 1
1 9996 1
2 Number of bytes in Modbus msg 1
3 Reserved (always 0) 1
4 to 248 Modbus message received 245
249 9996 1
The ladder logic should copy and parse the received message and control the
processor as expected by the Client device. The processor responds to the pass-
through block with a write block.
Response Block 9996 from Processor to Module
Word Offset Description Length
0 9996 1
1 to 247 Spare 247
This informs the module that the command has been processed and can be
cleared from the pass-through queue.