While not common, BCPii may occasionally experience communication delays or interruptions of service between itself and the targeted CPC and its associated support element. BCPii provides a mechanism through its BCPii communication error class of events to detect these interruptions and to allow an application to know when these interruptions of service have been resolved.

BCPii keeps a heartbeat between itself and each CPC where its applications desire connectivity. If BCPii fails to receive its regular heartbeat from an SE associated with a CPC, BCPii attempts a communication flow to this SE. If the SE responds successfully to this communication attempt by BCPii, BCPii signals a temporary communication error, (ENF QUAL value 02010001), meaning that the reason for the heartbeat not being received is not known, but the communication path between BCPii and the SE seems to be operational at this time. During the past few minutes, one or more events may have been lost.

If the SE does not respond to the BCPii communication attempt, BCPii assumes that there is a serious communication problem and signals a permanent communication error, (ENF QUAL value 02010002). At this point, no HWIEVENT or HWICMD API requests to this CPC are processed by BCPii and no event delivery take place for events registered on this CPC and its images. BCPii closes its internal connections with the CPC and cleans up resources associated with command processing and event delivery to and from this CPC.

BCPii then regularly attempts to restart its command processing and event delivery connections to this CPC. When this connection to the CPC has been re-established, BCPii signals a communication available event, (ENF QUAL value 02010003). At this point, applications currently having valid connections to this CPC and its images are allowed to use the HWIEVENT and HWICMD APIs to the CPC and its images. Receipt of events originating from the CPC and its images commence once again.

An application may choose to register for these communication availability events via the HWIEVENT ADD service (EventIDs parameter value Hwi_Event_HwCommError), or it may choose to use the ENFREQ LISTEN macro to listen for these events apart from any specific BCPii connection.