Hello,

Is there any way to tell when a CAN message has been received? Other systems call it an "update pin" and I think in CANOpen there is something called a "heartbeat." I have a control system with several controllers and absolutely must know that all the other devices are online, otherwise I flash a warning on the display and shut down operations. I figure there is an easy way to do this, as the only way I came up with (in theory, not practice) is to continuously change a variable from the sending device, and look for that variable to change on the PV750. If it doesn't change every x seconds, CAN communications is lost. Seems like a tough work around though!

Thanks!
Phil

CAN variables initialize invalid and they also turn invalid 10 seconds after the last time they were received.
You can use a lamp gauge to show text or and image when a variable's value is invalid, just check the box "Shown when inactive".

Thanks ksaenz -

While that does help a little, is there any other way? With the machinery I operate, a whole lot of damage can be done in 10 seconds!! (Including explosions, death, dismemberment....).

Thanks,
Phil

In that case I think a heartbeat would be a better option.
Create a state machine to show a warning after a timer of x milliseconds.
Add an "on change" event to your heartbeat variable. If you can't implement a hearbeat variable on your sending device you can pick an unused byte (always 0xFF).
The "on change" event should reset the timer. If you are using an unused byte, also change the value to something other than 0xFF, that way when it is received again it will trigger the "on change" event.
If the variable is not received before the timer expires you should see the warning.

hi kseanz,

Thanks! That is perfect, nice and simple.