Communications System; Tag Data Link Communications Method - Omron CJ1W-EIP21 Operation Manuals

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 Unit, the data transmission period is set for each connection as the
RPI.
The target device will send data (i.e., output tags) once each RPI, regardless of the number of nodes.
Also, the heartbeat frame is sent from the originator to the target for each connection. The target uses
the heartbeat to check to see if errors have occurred in the connection with the originator. The data
transmission period of the heartbeat frame depends on the RPI settings.
Heartbeat Frame Transmission Period
• If packet interval < 100 ms, the heartbeat frame transmission period is 100 ms.
• If packet interval ≥ 100 ms, the heartbeat frame transmission period is the same as the RPI.
Example:
In this example, 2 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.
10 ms
15 ms
10 ms
12-2
Node 1
Output data 1
Target
Connection 1 heartbeat
Output data 2
Connection 2 heartbeat
Output data 1
Output data 2
Output data 1
CJ-series EtherNet/IP Units Operation Manual for NJ-series CPU Unit (W495)
Node 2
Originator
100-ms interval
100-ms interval