LEDs for the two serial ports are located on the FX30E/FX60E’s bottom board on the opposite side of the RS-232 and RS-485 ports (Figure 7). Labels COM1 and COM2 correspond to the software configuration of the COM ports. LEDs show, transmit, and receive activity for the serial ports and optional modem.
Note: You must remove the cover to see the serial port LEDs. See Removing and replacing the cover.
- The yellow Transmit LED indicates that the FX30E/FX60E is sending data out the serial port over a communications line to a connected device.
- The green Receive LED indicates that the FX30E/FX60E is receiving data from a connected device.
These LEDs are driven by pulse detectors that provide a fixed on-time sequence when data is detected on the port. If the receive LED is on constantly, a problem with the communications channel may be present, such as a shorted wire or reversed wiring.