Post by tyronnosaurus on ReceiveWatchdog FB not working on J1939 P2P PGNs
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(Post)
Hi guys. I've got a device that sends a status message over J1939 and a PLC running Codesys to receive it. This message uses a P2P PGN (as opposed to a broadcast PGN). Codesys can only read it if I mark the J1939_ECU as "Local" (see screenshot 1). The message is received correctly, that is not the problem. The problem is detecting if the message stops being received. Local ECUs have no Watchdog checkbox to detect if the message has been received in the last X seconds. In order to implement a watchdog, I've used a ReceiveWatchdog FB. The same code works well for any non-P2P message, but doesn't work for this particular P2P message I'm trying to monitor. Even if I physically disconnect the device, ReceiveWatchdog.xBusy stays True, and ReceiveWatchdog.xError never triggers due to a timeout error. Is there any caveat in the ReceiveWatchdog FB that makes it unable to monitor P2P PGNs in Local J1939_ECUs?
Last updated: 2024-07-11
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