MD485 indicator LEDs

The MD485 has two red LEDs. When 12V power is applied, the LEDs light for one second. The LEDs then begin flashing once every two seconds, while there is no activity on the ports.

When the RS-485 port is an active port, the LED nearest that connector (labeled B in The MD485 has a ground lug that should be attached to earth ground, and LEDs that indicate traffic on the ports.) indicates traffic on the RS-485 port, and the other LED (labeled A) indicates traffic on the other active port (CS I/O or RS‑232). When CS I/O and RS‑232 are the active ports, the LED between the CS I/O connector and the RS-232 connector (A) indicates activity on the CS I/O port, and the other LED (B) indicates traffic on the RS-232 port. When data is being received and transmitted, the LEDs will flash. The LED for the port that is transmitting will be on more than the LED for the receiving port.

The LED nearest the RS-485 (B) connector will blink twice a second to indicate an RS-485 receiving error. This most likely indicates a wiring problem between the RS-485 ports of the base and remote MD485s.