I'm trying to understand how the various timing parameters in the CAN Port Settings interact. I've read the help and tested various combinations, but I'm running into some conflicts and misunderstandings. I'm using VeriStand 2018. Here are some of my findings and questions:
I'd really appreciate if NI could weigh in here. In the case of the first problem, there appears to be a huge gap between the help and my observations in a very simple-to-reproduce case. In the case of the second problem, I'd mostly like to know the theory of operation of the setting. The help does little to clarify the actual impact of this setting and how/why/when you'd set it. Some documentation like the "Parallel" vs "Low Latency" execution settings would go a long way to help out.
Solved! Go to Solution.
I escalated this to NI and got some clarification.
The IFPR field is not used as a decimation factor like the help states. It is used to calculate the decimation factor (DF) with this equation:
DF = PCL_Rate/IFPR
The IFPR used in that equation is the highest IFPR configured for all inlined incoming/outgoing CAN, LIN, and Flexray ports configured in the entire system definition. So, if you had a PCL of 1 kHz with one CAN port with inlined incoming frames of 100 Hz and another CAN port with inlined outgoing frames of 10 Hz, the decimation factor used for all inlined frames for both ports would be (1kHz)/(100 Hz) = 10. So all inlined CAN traffic would operate at (1 kHz)/10 = 100 Hz.
CAR 745144 was filed to clarify the help.