What is the common COM point of the PLC and the inverter? Is it positive?
It depends on your PLC and inverter I / O is what type, the most simple can be divided into two kinds of NPN and PNP, NPN COM point is negative, PNP COM is positive.
Generally refers to the common, and most of the negative
Plc is divided into two kinds of transistor output and relay output, com side may be connected to the high level may also be connected to the low level, the general input com port then low, the output port com mouth high, specifically what to take See the data sheet. Inverter is the same, the inverter has 24v com side and 10v com side, can not be connected together, com side generally low.
