34 Rockwell Automation Publication 5094-UM001E-EN-P - April 2020
Chapter 1 Digital I/O Module Operation in a Logix 5000 Control System
When the RPI is less than the program scan length, the output points can change
values multiple times during a program scan. The owner-controller does not
depend on the program scan to complete to send data.
These events occur when the controller sends data to a FLEX 5000 output
module.
1. Data is sent in one of the following ways:
• If the controller is directly connected to the EtherNet/IP network, it
broadcasts data to the network.
In this case, skip to step 3
.
• If the controller is connected to the EtherNet/IP network via a
communication module, the controller transmits the data to the
backplane.
In this case, proceed to step 2
.
2. The EtherNet/IP communication module transmits the data to the
EtherNet/IP network.
3. The FLEX 5000 EtherNet/IP adapter in the FLEX 5000 I/O system
receives the data from the network and transmits it to the backplane.
4. The digital output module receives the data from the backplane and
behaves as dictated by its configuration.
Output Module to Controller Data Transmission
When a FLEX 5000 output module receives new data and the requested data
value is present on the RTB, the output module sends, or ‘echoes’, a data value
back to the controller and to the rest of the control system. The data value
corresponds to the signal present at its terminals. This feature is called Data Echo
.
In addition to the Data Echo, the output module sends other data to the
controller at the RPI. For example, the module alerts the controller if a short
circuit condition exists on the module.
The following events occur when a FLEX 5000 output module sends data to the
controller at the RPI.
1. The module sends the data to the backplane.
2. The FLEX 5000 EtherNet/IP adapter in the FLEX 5000 I/O system
sends the data over the EtherNet/IP network.
3. One of the following occurs:
• If the controller is directly connected to the EtherNet/IP network, it
receives the input data from the network without need for a
communication module.
• If the controller is connected to the EtherNet/IP network through
another communication module, the module transmits the data to its
backplane and the controller receives it.
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