ttlappalainen/NMEA2000

SetN2kEngineDynamicParam does not support negative numbers for oil pressure

donmarlin opened this issue · 2 comments

donmarlin commented

I have a question about "SetN2kEngineDynamicParam" (PGN 127489).
Seems if I send a negative oil pressure out using N2K, it is not represented correctly on the bus.
The function prototype declares this as a double so I assumed signed values would be handled ok.

For example, sending -7000pa (~-1 psi) out using "SetN2kEngineDynamicParam", the value on the bus is actually showing as 6553400.
I am reading back using the "ParseN2kEngineDynamicParam" on a separate device as well as the Actisense NMEA Reader app.

I will work around since negative oil pressure is abnormal and I can clamp to zero. I was only wondering if it was something with my environment or my understanding. Thanks in advance

ttlappalainen commented

You can not set negative values for any pressure on engine dynamic PGN. If you set, library changes them to out of range value 6553400 Pa

donmarlin commented

Thanks for the reply, appreciate the timely feedback.