MVI56E-MNETC/MNETCXT ♦ ControlLogix Platform Reference
Modbus TCP/IP Client Enhanced Communication Module - Client/Server User Manual
ProSoft Technology, Inc. Page 107 of 172
September 20, 2018
The Read Block ID is an index value used to determine where the 200 words of
data from module memory will be placed in the ReadData[x] controller tag array
of the ControlLogix processor. Each transfer can move up to 200 words (block
offsets 2 to 201) of data. In addition to moving user data, the block also contains
status data for the module. The Write Block ID associated with the block requests
data from the ControlLogix processor.
During normal program operation, the module sequentially sends read blocks
and requests write blocks.
For example, if the application uses three read and two write blocks, the
sequence will be as follows:
R1W1R2W2R3W1R1W2R2W1R3W2R1W1
This sequence will continue until interrupted by other write block numbers sent by
the controller or by a command request from a node on the Modbus network or
operator control through the module’s Configuration/Debug port.
Status Data in Read Block
The following table describes in more detail the status information found in the
Read Block.
This value is incremented each time a complete
program cycle occurs in the module.
This field contains the total number of read blocks
transferred from the module to the processor.
This field contains the total number of write blocks
transferred from the processor to the module.
This field contains the total number of blocks
successfully parsed that were received from the
processor.
Command Event Block
Count
This field contains the total number of command
event blocks received from the processor.
This field contains the total number of command
blocks received from the processor.
This field contains the total number of block errors
recognized by the module.
Client 0 command
execution word
Each bit in this word enables/disable the commands
for Client 0. If the bit is set, the command will
execute. If the bit is clear, the command will be
disabled. This data is set in the output image
(WriteBlock) from the ladder logic.
Client 1 to Client 29
command execution words
These 29 words are used for each of the other 29
Clients in the module. This data is set in the output
image (WriteBlock) from the ladder logic.
The product ID code for the module
The firmware version number for the module
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