CAN communication with ArCan - Receive wrong ID issue

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1

Hello,

we are facing out a problem with CAN communication (29 bit).

The hardware is a 4PPC80 with CAN on IF7.
I would like to communicate with a device via CAN with ArCan. I am trying to read some message with “ArCanReceive ()”.
The strange things is that if I configure “arCAN_RECEIVE_ALL” the FC returns me some IDs.

In my opinion they are not the correct IDs because if I set such IDs in input to the FB and configure “arCAN_RECEIVE_SINGLE_ID” the FB doesn’t give me back any result.

In my opinion there are some communication issue.

I read a lot and I measure the resistance between CAN H and CAN L.

I saw that, with all powered off, just the device has 40 ohm.
It can be the problem for such issue? How to diagnostic it?
Any solution?

I also try with anoter device that communicates via CAN (11 bit).
I inserted some 120 ohm resistance between CAN H and CAN L and I arrive more or less al 30 oh. (less than 60 ohm requested).
I don’t find any problem with such device (I would expect the same behaviour of the first device)
Something strange to me.

Any idea?

Thanks for the support

Giovanni

2

On a C80 the terminating resistor can be activated in the configuration of the CAN-interface.

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The OPS leds also reflects the activation of the terminating resistor.
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3

Thanks but I alredy tried both solutions, so with and without terminating resistor activated.
It seems that I receive on the PLC wrong IDs.
With terminating resistor on, I saw that IDs received are much more similar to the ID indicated in the manual of the device.

The OPS2 is yellow with both solutions, with and without terminating resistor on PLC side.

Any experience of such behaviour?

Any idea?

Thanks,

Giovanni