Operating instructions

PTQ-MCM ♦ Quantum / Unity Platform Reference
Modbus Communication Module
Page 108 of 139 ProSoft Technology, Inc.
April 29, 2008
Both ports can operate in pass-thru mode simultaneously. If the port is
configured for pass-thru swap the module will swap the data bytes (high
order/low order) before transferring the data to the processor.
Since the module transfers the data directly to the processor the PTQ-MCM
database is not updated during pass-thru operation.
Block Pass-Thru
The following modbus functions are supported during block pass-thru operation:
Function
Code
Description Code Maximum Count Quantum Memory Area
5* Force Single Coil 1 0x (coil)
6 Preset Single Register 1 4x (holding register)
15* Force Multiple Coils 800 0x (coil)
16 Preset Multiple Registers 125 4x (holding register)
*
Not supported during block pass-thru with byte swap.
You must configure the following parameter from the configuration file during
block pass-thru operation:
Pass Thru Address : 1000 # Pass-Thru address
This parameter sets the holding register address where the pass-thru block will
be copied at the processor memory. The module will add 400001 to this value,
therefore for the example above the block will be copied starting at holding
register address 401001.
The module writes the pass-thru block to the processor during one scan.
Therefore the user should add logic in order to detect the presence of one of the
block ID's listed in this section. After the block is handled the program should
reset the block ID in order to use the Block ID change as a trigger for the
incoming block.
The following flowchart shows the implementation of the processor logic to copy
the data from the pass-thru block.
Is Pass-Thru block
ID equal to 0?
Copy the Pass-Thru
block.
Set Pass-Thru block
ID to 0.
N
Y