12-1 Communications System; Tag Data Link Communications Method - Omron NX Series User Manual

12 Communications Performance and Communications Load

12-1 Communications System

12-1-1

Tag Data Link Communications Method

Requested Packet Interval (RPI) Settings
In tag data links for the EtherNet/IP port, the data transmission period is set for each connection as the
RPI.
The target device sends data (i.e., output tags) based on the specified RPI, regardless of the number
of nodes.
Also, the heartbeat frame is sent from the originator to the target device for each connection. The tar-
get device uses the heartbeat to check if any errors have occurred in the connection with the origina-
tor. The data transmission period of the heartbeat frame depends on the RPI settings.
Heartbeat Frame Transmission Period
• If packet interval is shorter than 100 ms, the heartbeat frame transmission period is 100 ms.
• If packet interval is equal to or larger than 100 ms, the heartbeat frame transmission period is the
same as the RPI.
Example)
In this example, two tag data link connections are set for node 2 (the originator) and node 1 (the tar-
get).
The RPI for output data 1 is set to 10 ms.
The RPI for output data 2 is set to 15 ms.
In this case, output data 1 is sent from node 1 to node 2 every 10 ms, and output data 2 is sent from
node 1 to node 2 every 15 ms, as shown in the following diagram.
Also, data is sent from node 2 (the originator) to node 1 (the target) with a heartbeat of 100 ms for
connection 1 and a heartbeat of 100 ms for connection 2.
12-2
NX-series EtherNet/IP Unit User's Manual (W627)