You are called at home at 3am by an unskilled machine operator with a suspected network related problem; the controller LEDs are all normal but the output module’s communications LED is not on. The operator has verified the cable is functional and correctly connected from the communication module to the switch.
What is the next check that you ask the unskilled machine operator to make?
A. Log onto the switch using the console port and check that IGMP snooping is enabled
B. Open wireshark and check whether the controller is issuing a forward open instruction to the device
C. Open the diagnostic faceplate on the HMI for the control panel switch and check that the relevant ports are enabled and not in alarm
D. Open Studio 5000 and check the module status tab for the affected output module
