Clearing / Releasing a priority about bacpypes

[JoelBender]

It looks like you are writing the entire priority array in one shot when you should be writing a Null to the to the Present_Value property and providing the priority as a the parameter to the Write Property Request. The Priority_Array is a read-only property.

>>> request = WritePropertyRequest(destination=Address("1.2.3.4"),
...     objectIdentifier=('analogValue', 1), propertyIdentifier='presentValue',
...     propertyValue=Any(),
...     priority=8
... )
>>> request.propertyValue.cast_in(Null())

You really don't want to stomp on the priority array items that have been written by other, perhaps higher priority processes, and you don't want to have to read the whole thing then write it back out again for the same reason, so it's read-only.

[kheldaroz-droid]

thanks Joel - that actually makes sense - maybe I'm getting the hang of python / BACnet

updated code for reference

`def release_bacnet_priority(device_instance, addr, object_type, priority=8):
logging.info(f"Releasing Priority {priority} on Device {device_instance} at {addr} ({object_type})")

# Create the write request
request = WritePropertyRequest(
    objectIdentifier=(object_type, device_instance),
    propertyIdentifier='presentValue',
    propertyValue=Any(),
    priority=priority

)
request.propertyValue.cast_in(Null())
request.pduDestination = Address(addr)
iocb = IOCB(request)

# Attach the address to the IOCB instance
iocb.addr = addr
iocb.object_type = object_type

callback_function = lambda iocb, prop='presentValue': on_property_release_response(iocb, prop)
iocb.add_callback(callback_function)
this_application.request_io(iocb)

def on_property_release_response(iocb, prop):
if iocb.ioError:
logging.error(f"{color.RED}Error Releasing to property {prop} on {iocb.addr} ({iocb.object_type}): {iocb.ioError}{color.END}")
else:
logging.info(f"{color.GREEN}Successfully Released Priority on property {prop} on {iocb.addr} ({iocb.object_type}){color.END}")`