ProSoft Technology MVI56E-MNETCR - Manual (Page 103)

MVI56E-MNETCR ♦ ControlLogix Platform Reference
Modbus TCP/IP Multi Client Enhanced Communications Module for Remote Chassis User Manual
ProSoft Technology, Inc. Page 103 of 159
June 14, 2011
Event Command Blocks (2000 to 2029)
Event command control blocks send Modbus TCP/IP commands directly from the
ladder logic to one of the clients on the module. The following table describes the
format of these blocks.
Offset Description Length
0 2000 to 2029 1
1 to 4 IP Address 4
5 Service Port 1
6 Slave Address 1
7 Internal DB Address 1
8 Point Count 1
9 Swap Code 1
10 Modbus Function Code 1
11 Device Database Address 1
12 to 41 Spare 30
Use the parameters passed with the block to construct the command. The IP
Address for the node to reach on the network is entered in four registers (1 to 4).
Each digit of the IP address is entered in the appropriate register.
For example, to interface with node 192.168.0.100, enter the values 192, 168, 0
and 100 in registers 1 to 4. The Service Port field selects the TCP service port
on the server to connect. If the parameter is set to 502, a standard MBAP
message will be generated. All other service port values will generate a Modbus
command message encapsulated in a TCP/IP packet.
The Internal DB Address parameter specifies the module’s database location to
associate with the command. The Point Count parameter defines the number of
points or registers for the command. The Swap Code is used with Modbus
functions 3 and 4 requests to change the word or byte order. The Modbus
Function Code has one of the following values 1, 2, 3, 4, 5, 6, 15 or 16. The
Device Database Address is the Modbus register or point in the remote slave
device to be associated with the command.
When the module receives the block, it will process it and place it in the
command queue. The following table describes the format of this block.
Word Description
0 This word contains the block 2000 identification code to indicate that this
block contains a command to execute by the Client Driver.
1 to 4 These words contain the IP address for the server the message is intended.
Each digit (0 to 255) of the IP address is placed in one of the four registers.
For example, to reach IP address 192.168.0.100, enter the following values in
words 1 to 4 → 192, 168, 0 and 100. The module will construct the normal
dotted IP address from the values entered. The values entered will be anded
with the mask 0x00ff to insure the values are in the range of 0 to 255.