The PSAVANpoll component is a protocol helper component. It must be placed directly above a VAN component. The PSAVANpoll component can be used with ECUs that use inframe responses (IFR) to answer requests. In this case not only the host has to generate the request but also must poll for the response. Since the response message can be polled while the ECU is updating its IFR object it is necessary to secure the access.
The PSAVANpoll component assumes that user data of the response message is surrounded and in this way protected by two copies of a byte wide counter where both copies contain the same value when no update is in progress.
The PSAVANpoll component starts polling when a transmit data event's source ID matches a certain ID configured in the PSAVANpoll component. The time between two poll cycles can be configured. After a configurable time polling stops unless retrigger mode is activated and more IFR messages arrive.
When receiving IFR messages the PSAVANpoll component strips the counter copies from the response and delivers only the user data to the next component.
The PSAVANpoll component is configured as a stream component in its upper info block. This enables the component to directly connect to protocol components like BDiag. The PSAVANpoll component validates the data size of transmit data events. In case that a transmit data event contains more data than the VAN component can handle the PSAVANpoll component rejects the event with the flags AIDA_nSendError and AIDA_nOverrun set in the dwFlags member of the AIDA event.
When the stack goes online the PSAVANpoll component immediately starts a polling cycle but ignores the first valid IFR message.
A value of 1 activates retrigger mode. When retriggering is activated any counter change in IFR responses retriggers the total poll time. PollRetrigger should be set to 1 when the ECU can generate fragmented answers.
When setting PollRetrigger to 2 polling stops as soon as any counter change in IFR responses is detected. This can be used to reduce VAN bus activities when no fragmentented answers are expected.
Any value other than the ones described above are treated like a value of 0.
AIDA Overview, list of AIDA components