ProSoft Technology MVI71-MCM - Manual (Page 72)

MVI71-MCM ♦ PLC Platform Reference
Modbus Communication Module
Page 72 of 111 ProSoft Technology, Inc.
December 28, 2007
Offset Description Length
3 Command index 1
4 Command index 1
5 Command index 1
6 Command index 1
7 to 63 Spare 57
Blocks in the range of 5001 to 5006 are used for Modbus Port 1, and blocks in
the range of 5101 to 5106 are used for Modbus Port 2. The last digit in the block
code defines the number of commands to process in the block. For example, a
block code of 5003 contains 3 command indexes that are to be used with
Modbus Port 1. The Command index parameters in the block have a range of 0
to 99 and correspond to the master command list entries.
The module responds to a command control block with a block containing the
number of commands added to the command queue for the port. The following
table describes the format for this block.
Read Block
Offset Description Length
0 5001 to 5006 or 5101 to 5106 1
1 Write Block ID 1
2 Number of commands added to command queue 1
3 to 63 Spare 61
Read Current Configuration
This block is sent from the PLC processor to the module to force the module to
write its current configuration back to the processor. This function is used when
the module's configuration has been altered remotely using database write
operations. The write block contains a value of -9000 in the first word. The
module will respond with blocks containing the module configuration data. Ladder
logic must handle the receipt of these blocks. The blocks transferred from the
module are as follows:
Block -9000, General Configuration Data:
Offset Description Length
0 -9000 1
1 -9000 1
2 to 7 Backplane Setup 6
8 to 32 Port 1 Configuration 25
33 to 57 Port 2 Configuration 25
58 to 63 Spare 6