Allen-Bradley 1407-CGCM-DLR User Manual page 142

Chapter 6 CGCM-DLR Unit Software Interface
142
Connection Behavior During Configuration
The CGCM-DLR unit operates with an active Class 1 connection with a
ControlLogix programmable controller that you have programmed and
configured. The Class 1 connection is made through the Add-on Profile. The
CGCM-DLR unit controls the state of 2 bits in the Input data table to interact
with the controller during configuration:
• ConfigRcvd - indicates that the CGCM-DLR unit has accepted a valid
Configuration Write message
• UnschdWriteRcvd - indicates that the CGCM-DLR unit has accepted a
valid Unscheduled Write message
Two types of connection-related services are involved in the configuration of the
CGCM-DLR unit:
• Forward Open - When a connection is first established, for example, when
the Add-on Profile is first configured or the CGCM-DLR unit is powered
on, a Forward Open service is executed. The ConfigRcvd and
UnschdWriteRcvd bits initial states are de-asserted. The controller writes
the Configuration data table automatically, and when the CGCM-DLR
unit accepts this write, it sets the ConfigRcvd bit. This bit enables the user
program logic rung that controls the Unscheduled Write message. When
the CGCM-DLR unit accepts the Unscheduled Write, it sets the
UnschdWriteRcvd bit.
• A Null Forward Open is executed when all of these conditions are met:
– A connection is already established.
– A change to the Configuration or Unscheduled Write data tables is
made in the module profile tabs.
– Apply or OK is clicked.
The controller attempts to write the Configuration automatically. If
excitation is not enabled, the CGCM-DLR unit accepts a valid
configuration write. If excitation is enabled, the configuration write is
rejected. The CGCM-DLR unit de-asserts the UnschedWriteRcvd bit
during the execution of a Null Forward Open and thus re-enables the user
program logic rung that controls the Unscheduled Write message. When
the CGCM-DLR unit accepts the Unscheduled Write, it sets the
UnschdWriteRcvd bit.
In either case, when the UnschedWriteRcvd bit is asserted, the CGCM-DLR
unit begins to process Schedule Write (Output) data and is ready for normal
operation that is based on the configuration and output commands received. The
CGCM-DLR unit ignores any Scheduled Write (Output) data if the
UnschedWriteRcvd bit is not asserted.
Rockwell Automation Publication 1407-UM002B-EN-P - February 2019