When the OMRON CS1W-ETN21 or equivalent communication unit is connected via TCP communication, if the TCP communication is disconnected due to some factor such as turning off the PC, the PLC side is designed to maintain the open state.
FA-Panel's "Panel Server" tries to reconnect when the connection is lost, but since TCP/IP open retention is in effect on the PLC side, it continues to be unable to connect.
The following is how to check if the connection is abnormal. Even if the "Panel Server" is offline, the TCP of the H/W lamp of the "CS1W-ETN21" is always ON. When the communication connection is being disconnected, this lamp turns off. This operation can be changed by changing the PLC survival check setting (TCP/IP keep-alive) setting in the "CX-Programmer" to change the TCP/IP port open delay time in the event of a communication error.
Comparison of setting values
- [Set value: 0] TCP/IP line open 120 minutes
- [Set value: 1] TCP/IP line open 9 times every 75 seconds starting 1 minute later (NG) -> open after about 10 minutes
Recovery Method
- Wait for the set TCP/IP keep-alive time
- PLC reset (power off)
Due to the above, we recommend that the communication protocol between the "Server" and the PLC be UDP instead of TCP.
When using UDP communication, the following settings are recommended.
- Select the automatic generation method (dynamic).
- To separate the nodes, set a different node number on the PC side for each folder in the unit.
- The port number on the computer side of the unit should be automatic.
*If the setting is fixed, communication will not be possible when multiple units are set.