ProSoft Technology MVI71-MCM - Manual (Page 66)

MVI71-MCM ♦ PLC Platform Reference
Modbus Communication Module
Page 66 of 111 ProSoft Technology, Inc.
December 28, 2007
Master Command Blocks
Each port on the module can be configured as a Modbus master device
containing its own list of one hundred commands.
Each command has the following structure:
Offset Parameter
0 Enable
1 Internal
Address
2 Poll Interval
3 Count
4 Swap
5 Slave
Address
6 Function
7 Destination
Address
8 Spare
9 Spare
For information about these parameters, refer to the Configuring the Module
section under Modbus Master Commands.
The commands are read from the processor using the following Write Block ID's:
Modbus Port 1 - 6000 to 6016 and Modbus Port 2 - 6100 to 6116. The module
will sequentially poll for each block from the processor. Ladder logic must handle
each and every one of the data transfers (the sample ladder logic already
handles this). The structure of each block is shown in the following table.
Offset Description Length
0 6000 to 6016 and 6100 to 6116 1
1 to 10 Command Definition 10
11 to 20 Command Definition 10
21 to 30 Command Definition 10
31 to 40 Command Definition 10
41 to 50 Command Definition 10
51 to 60 Command Definition 10
61 to 63 Command Definition Spare 3
Each block contains six commands. Because there are 100 possible commands,
the last block (6016 or 6116) should contain up to four commands.
As the list is read in from the processor and as the commands are processed, an
error value is maintained in the module for each command. The errors generated
by the module are listed in MVI71-MCM Command Error Codes (page 94).
Transferring the Command Error List to the Processor
You can transfer the command error list to the processor from the module
database. To place the table in the database, set the Command Error Pointer
parameter to the database location desired.
To transfer this table to the processor, make sure that the Command Error table
is in the database area covered by the Read Data.