inconsistent COV subscription response: noReponse vs timeout

[Mathadon]

When subscribing on a COV value of a binary input of an unreachable device, an error is to be expected. But unexpectedly, not the same error is thrown. In some cases the subscription acknowledgement iocb.ioError contains 'noResponse' and in other cases it contains 'timeout'. Would it make sense to revise bacpypes such that the same error is returned each time or is there in fact a difference between the two?