ProSoft Technology MVI56E-MNETR - Manual (Page 57)

Configuring the MVI56E-MNETR Module MVI56E-MNETR ♦ ControlLogix Platform
User Manual Modbus TCP/IP Interface Module with Reduced Data Block
ProSoft Technology, Inc.
Page 57 of 153
August 31, 2009
2.1.5 [MNET Client x Commands]
The [MNET C LIENT X C OMMANDS ] section of the configuration sets the Modbus
TCP/IP Client command list. This command list polls Modbus TCP/IP Server
devices attached to the Modbus TCP/IP Client port. The module supports
numerous commands. This permits the module to interface with a wide variety of
Modbus TCP/IP protocol devices.
The function codes used for each command are those specified in the Modbus
protocol (page 121). Each command list record has the same format. The first
part of the record contains the information relating to the MVI56E-MNETR
communication module, and the second part contains information required to
interface to the Modbus TCP/IP Server device.
Command List Overview
In order to interface the MVI56E-MNETR module with Modbus TCP/IP Server
devices, you must construct a command list. The commands in the list specify
the Server device to be addressed, the function to be performed (read or write),
the data area in the device to interface with and the registers in the internal
database to be associated with the device data. The Client command list
supports up to 100 commands.
The command list is processed from top (command #0) to bottom. A poll interval
parameter is associated with each command to specify a minimum delay time in
tenths of a second between the issuance of a command. If the user specifies a
value of 10 for the parameter, the command will be executed no more frequently
than every 1 second.
Write commands have a special feature, as they can be set to execute only if the
data in the write command changes. If the register data values in the command
have not changed since the command was last issued, the command will not be
executed.
If the data in the command has changed since the command was last issued, the
command will be executed. Use of this feature can lighten the load on the
network. In order to implement this feature; set the enable code for the command
to a value of 2.