ProSoft Technology MVI56E-MNETR - Manual (Page 111)

Reference MVI56E-MNETR ♦ ControlLogix Platform
User Manual Modbus TCP/IP Interface Module with Reduced Data Block
ProSoft Technology, Inc.
Page 111 of 153
August 31, 2009
Cold Boot
This block is sent from the ControlLogix processor to the module (output image)
when the module is required to perform the cold boot (hardware reset) operation.
This block is sent to the module when a hardware problem is detected by the
ladder logic that requires a hardware reset. The following table describes the
format of the control block.
Offset Description Length
0 9999 1
1 to 41 Spare 41
Pass-Through Control Blocks
If the module is set for pass-through operation by placing a value of 1 to 3 in the
configuration file parameter Pass-Through Mode, the module will send special
blocks to the module when a write request is received from a client. Any Modbus
function 5, 6, 15 or 16 commands will be passed from the server to the processor
using this block identification numbers 9956 to 9961, 9970 and 9996. Ladder
logic must handle the receipt of these blocks and to place the enclosed data into
the proper controller tags in the module.
There are two basic modes of operation when the pass-through feature is
utilized: Unformatted (code 1) and Formatted (code 2 or 3). The unformatted
mode will pass the message received on the server directly to the processor
without any processing. The following table describes the format of the read
block.
Unformatted
Unformatted Pass-Through Command (Read Block)
Offset Description Length
0 9996 1
1 Number of bytes in Modbus msg 1
2 Reserved (always 0) 1
3 to 40 Modbus message received 38
41 9996 1
The ladder logic should copy and parse the received message and control the
processor as expected by the master device. The processor must respond to the
pass-through control block with a write block. The following table describes the
format of the write block.
Unformatted Pass-Through Command (Write Block)
Offset Description Length
0 9996 1
1 to 41 Spare 41
This informs the module that the command has been processed and can be
cleared from the pass-through queue.