ProSoft Technology MVI69-MCM - Manual (Page 126)

Reference MVI69-MCM ♦ CompactLogix or MicroLogix Platform
User Manual Modbus Communication Module
Page 126 of 167 ProSoft Technology, Inc.
March 22, 2011
Write Block - Event Command
Here is the structure of the Event Command output image write block.
Offset Description Length (words)
0 Block Number: 1000 to 1255 or 2000 to 2255 1
1 Internal DB Address 1
2 Point Count 1
3 Swap Code 1
4 Function Code 1
5 Device Address 1
6 to ( n ) Spare
( n ) = 60, 120, or 240 depending on the Block Transfer Size parameter (refer to the configuration
file).
The Block Number defines the MODBUS port to be considered. The slave
address is represented in the block number in the range of 0 to 255, added to
1000 for commands to be sent out Port 1 or to 2000 for commands to be sent out
Port 2. The sum of these two values determines the block number to use.
Example1: To send an Event Command to Slave 34 from Master Port 1, use
Block Number 1034.
Example 2; To send an Event Command to Slave 227 from Master Port 2, use
Block Number 2227
Note: Slave address 0 is a broadcast address. Commands with this address will affect all slaves
on the network. Not all addresses in the range 1 to 255 are valid for all slave devices. This is
especially true for addresses 248 through 255.
Use the parameters passed with the block to construct the command.
The
I NTERNAL DB A DDRESS
parameter specifies the module’s database
location to associate with the command.
The P OINT C OUNT
parameter defines the number of registers for the
command.
The S WAP C ODE
changes the word or byte order.
The D EVICE A DDRESS
parameter defines the MODBUS address on the target
MODBUS device to consider.
The F UNCTION C ODE
parameter is one of those defined in the ProSoft
MODBUS Command Set documentation.
The parameter fields in the block should be completed as required by the
selected function code. Each command type 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 command block with a
input image read block.