Module Configuration
MVI56-DH485R
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ControlLogix Platform
User Manual
DH485 Interface Module for Remote Chassis
ProSoft Technology, Inc.
Page 29 of 97
August 27, 2009
2.4
[DH485 Port x Commands]
The [DH485 Port x Commands] section for each port defines the commands to
be issued by the module to other devices on the network. These commands can
be used for data collection and/or control.
2.4.1 Command List Overview
In order to interface the MVI56-DH485R module to act as a master device, you
must construct a command list for each port. The commands in the list specify
the node 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 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 seconds 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 10 seconds.
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.
