Rockwell Automation 1756-DHRIO_DHRIOXT ControlLogix Data Highway Plus-Remote I/O Communication Interface Module - Manual (Page 106)

106 Rockwell Automation Publication 1756-UM514C-EN-P - June 2014
Chapter 9 Using the 1756-DHRIO and 1756-DHRIOXT Modules in Remote I/O Applications
The 1756-DHRIO and 1756-DHRIOXT modules entry in the I/O
configuration tree specifies the status connection between the scanner function
on the 1756-DHRIO or 1756-DHRIXOT module and the ControlLogix
controller.
The adapter entries under the 1756-DHRIO and 1756-DHRIOXT modules in
the I/O configuration tree specify the connections between the ControlLogix
controller and the 1756-DHRIO or 1756-DHRIOXT module for each adapter’s
data.
Remote I/O Scanner Status A connection is used to exchange remote I/O scanner status as described
previously. The data from the 1756-DHRIO or 1756-DHRIOXT module
contains the current state of the channels (A/B) that are configured for remote I/
O. The data from the ControlLogix controller represents an update used by the
1756-DHRIO or 1756-DHRIOXT module to maintain ownership.
This data exchange is continually updated and is responsible for maintaining
module awareness in the system.
TIP Enter a 1756-DHRIO or 1756-DHRIOXT module into the I/O configuration
tree only if at least one of the module’s channels is configured for remote I/
O.