ProSoft Technology MVI94-MCM-MHI - Manual (Page 79)

MVI94-MCM ♦ Flex I/O Platform Reference
Serial Communications Modbus Communication Module User Manual
ProSoft Technology, Inc. Page 79 of 109
March 29, 2011
Block Response from Module to Processor
Word Offset Description
0 This word contains the block 1000 to 1255 requested by the processor.
1 This word contains the next read request block identification code.
2 This word contains the result of the event request. If a value of one is present, the
command was issued. If a value of zero is present, no room was found in the
command queue.
3 Not used.
4 Not used.
5 Not used.
6 Not used.
The ladder logic can examine word 2 of the input image to determine if the
module was able to execute the command. If invalid parameters are set in the
event request block, the command may still be placed in the queue and there will
be no error indication.
Command Blocks (2001 to 2006)
These control blocks are sent from the processor to the module to execute one
or more commands in the module's command list out the Modbus master port.
Commands selected for execution need not have the Enable Code set (1 or 2)
but must be valid commands. The format for this block is shown in the following
table.
Block Request from Processor to Module
Word Offset Description
0 Command queue block identification code of 2001 to 2006.
1 This word contains the index in the command list for the first command to be
entered into the command queue.
2 This word contains the index in the command list for the second command to be
entered into the command queue.
3 This word contains the index in the command list for the third command to be
entered into the command queue.
4 This word contains the index in the command list for the fourth command to be
entered into the command queue.
5 This word contains the index in the command list for the fifth command to be
entered into the command queue.
6 This word contains the index in the command list for the sixth command to be
entered into the command queue.
When the module receives one of these blocks, it examines word 0 of the output
image. This word defines the number of commands contained in the block. The
command count is determined by subtracting 2000 from the word value. This
permits the controller to set from one to six commands into the command queue.
The indexes submitted in the block should be valid for the command list. After the
module determines the number of commands to consider, it inserts each
command in the command queue. The response message sent from the module
to the processor is as follows: