Hello,
We have a same weird problem.
FMB640 is connected to K-line but do not see tacho data on one truck (other similar trucks with identical hardware are ok).
In configurator Tachograph Data section shows only some data - timestamp, VRN, VIN etc which could be received I think via CAN.
I have double checked the wiring connection and it seems everything is ok here.
Is it possible to see logs regarding K-line data readings somehow?
Thank you.