Operating instructions

Reference PTQ-MCM ♦ Quantum / Unity Platform
Modbus Communication Module
ProSoft Technology, Inc. Page 101 of 139
April 29, 2008
The parameter fields in the block should be completed as required by the
selected function code. Each command has its own set of parameters. When the
block is received, the module will process it and place the command in the
command queue. The module will respond to each event command block with a
read block with the following format:
Read Block: Event Command
Offset Description Length
0 0 1
1 Write Block ID 1
2 0=Fail, 1=Success 1
3 to n Spare
Word two of the block can be used by the processor logic to determine if the
command was added to the command queue of the module. The command will
only fail if the command queue for the port is full (100 commands for each queue)
or the command requested is invalid.
8.2.4 Command Control Block
The first 64 words of each block are reserved for command control. Each
command control block has a Block ID number (shown in parentheses below)
that identifies the command control instruction. The PTQ-MCM module supports
the following command control blocks:
 Event Command (1000 to 1247 Port 1; 2000 to 2247 Port 2)
 Command Control (5001 to 5006 Port 1; 5101 to 5106 Port 2)
 Warm Boot (9998)
 Cold Boot (9999)
The value in word 0 of this 64 word block is the block sequence number. This
number identifies whether the contents of the block have changed. This is the
actual trigger to send the control request to the module.
Processor logic must be built to handle the command control functionality. The
logic would typically follow these steps:
1 Move the block request to output command control area.
2 Move a new value to the output block sequence number.
3 If the input block sequence number equals the output block sequence
number + 1, copy the block response to appropriate variables in the module's
memory.