ProSoft Technology MVI71-MCM - Manual (Page 97)

Reference MVI71-MCM ♦ PLC Platform
Modbus Communication Module
ProSoft Technology, Inc. Page 97 of 111
December 28, 2007
Block Transfer instructions transfer data: the BTR instruction reads data from the
module and the BTW instruction writes data to the module.
If using side connect (requires side connect adapter) option, ladder logic is not
required to transfer data to the MVI71-MCM.
5.9.4 What is the procedure to change the module's configuration?
A simple boot operation will force the module to request configuration data. The
ladder logic can force the module to perform a Cold Boot or Warm Boot.
5.9.5 How do I set a Port Modbus Master command?
You can create Modbus commands using a PLC data file that is copied to the
BTW data file by the ladder logic. The sample ladder logic uses:
N11: Port 1 Master Commands
N12: Port 2 Master Commands
Ladder logic is necessary to copy the commands to the MVI71-MCM during the
boot operation (the sample ladder already handles it).
5.9.6 The Modbus Master Command is not working, what should I
do?
Look at the Command Error Menu in the debug port and write down the code
associated with the command index. Look for the meaning of the error code in
MVI71-MCM Command Error Codes (page 94) and ensure that the parameters
entered are valid.
If there is no error code in the Command Error Menu, the Modbus command
could refer to a different location than the one considered.
5.9.7 What is the Pass-Through feature?
An MVI71-MCM slave port can be configured for pass-through mode. This
causes every write command to write directly to the PLC, without modifying the
MVI71-MCM internal database. In order to accomplish this, every time a slave
pass-through port receives a write command, the module generates specific
blocks that allows ladder logic to handle each write command internally (refer to
the Pass-Through section).
5.9.8 How can I check a Slave's status connected to an MVI71-MCM
Master port?
The debug port allows the user to monitor every slave attached to a master port.