How do I unset the expecting reply bit?

[djlad]

Hi, I'm trying to unset the expecting reply bit in a ReadPropertyMultipleRequest to troubleshoot a device.

        request = ReadPropertyMultipleRequest(listOfReadAccessSpecs=readAccessSpecList)
        request.pduExpectingReply = 0
        request.pduDestination = Address(address)
        iocb = IOCB(request)
        deferred(self.request_io, iocb)

Is there something I'm missing? The expecting reply bit is still set.

I'm trying this because I'm occasionally getting abort reject reason 65 (noResponse) when I read from a "PurpleSwift bacnet_p2 gateway". I noticed that PurpleSwift's bacnet explorer reliably reads every time and doesn't have the expecting reply bit set.

Also, does reason 65 imply a timeout? Is it possible to increase the time before it times out?

[JoelBender]

Second question is easier, the 65 is an application layer timeout, so the APDU timeout and retry count has been exceeded. You can change those parameters by providing apduTimeout and numberOfApduRetries values in the LocalDeviceObject object that is created, the defaults of 3000 milliseconds and 3 are in the bacpypes.local.device module.

The first question is harder, I can confirm that turning off request.pduExpectingReply in your application doesn't propagate down so when the PDU hits the UDP communications virtual link layer it has been turned back on again. Humph.

[JoelBender]

Issue #472 created. A Wireshark pcap file with the working requests from the BACnet explorer and your not-working requests might reveal other problems.

[JoelBender]

When I was confirming there was a problem it turns out I was looking at the wrong bit. The gist here shows the stack is working correctly.