ProSoft Technology MVI56E-MNET/MNETXT - Manual (Page 120)

Reference MVI56E-MNET / MNETXT ♦ ControlLogix Platform
User Manual Modbus TCP/IP Interface Module
Page 120 of 181 ProSoft Technology, Inc.
April 23, 2014
Event Command Blocks (2000)
Note: Event Commands are not needed for normal Modbus command list polling operations and
are needed only occasionally for special circumstances.
During routine operation, the module continuously cycles through the user-
defined MNET Client 0 Command List (page 47), examining commands in the
order they are listed and sending enabled commands on the network. However,
the module also has a special command priority queue, which is an internal
buffer that holds commands from special function blocks until they can be sent
on the network.
When one or more commands appear in the command priority queue:
1 The routine polling process is temporarily interrupted.
2 The commands in the command priority queue are executed until the queue
is empty.
3 Then the module goes back to where it left off on the MNET Client 0
Command List and continues routine polling.
Event Command blocks send Modbus TCP/IP commands directly from controller
tags by ladder logic to the Client command priority queue on the module. Event
Commands are not placed in the module's internal database and are not part of
the MNET Client 0 Command List.
Block Request from Processor to Module
Word Offset Description Length
0 Block ID - This word contains block identification code 2000 to indicate
that the block contains a command to be executed by the Client driver. 1
1 to 4 IP Address - These four words contain the IP address of the destination
server. Each octet value (0 to 255) of the destination server's 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 ensure the values are in the range of 0 to 255.
4
5 Service Port - This word contains the TCP service port used in the
message. For example, to interface with a MBAP device, the word
should contain a value of 502. To interface with a MNET device, a value
of 2000 should be used. Any value from 0 to 65535 is permitted. A value
of 502 will cause a MBAP formatted message to be generated. All other
values will generate an encapsulated Modbus (serial-type) message. 1
6 Slave Address - This word contains the Modbus node address for the
message. This field should have a value from 1 to 247. 1
7 Internal DB Address - This word contains the internal Modbus address in
the module to use with the command. This word can contain a value
from 0 to 4999. 1
8 Point Count - This word contains the count parameter that determines
the number of digital points or registers to associate with the command. 1
9 Swap Code - This parameter specifies the swap type for the data. This
option is valid only for function codes 3 and 4. 1