Hello,
I'am using plc fatek fbs 40 ma i'am using usb-to- com adapter and rs232 cable the cable and usb adapter programed the plc without any problem and the simulation work and rx tx led light in plc but if relay or cantactor switch on and off the connection between plc and pc is faild and the connection not connect again else remove usb adapter and connect again
Knowing relay and contactor 220 v