PCD3.F27x and PCD2.F27xx M-Bus is not always short cut protected!
Those M-Bus cards have a short-cut protection on the bus but when the CPU isn't anymore power supplied and the F27x(x) card still has 24 V supply there is no short cut protection anymore!
The 36 Volts from the M-Bus will destroy some components on the concerned serial port of the card!
Use the same power supply for the CPU as for the PCDx.F27x(x) card or if for some reason a different power supply has to be used be aware that in case the CPU isn't power supplied that the M-Bus is NOT short-circuited!
PCD3 / Fxxx
Last update: 28.05.2015 13:39
First release: 22.10.2013 17:28