3.4.8.3 Metrology Pulse Outputs, Opto-Port Interface and Relay Coil Command Interface

PL360MB includes several metrology interfaces:
  1. Opto-Port for UART1.The Opto-Port for UART1 is composed of an infrared emitting diode and a phototransistor to allow electrically isolated communications with an external optical probe. See following figure.
    Figure 3-23. Opto-Port for UART1
  2. Opto-Port for Pulse Output. The user can measure the VARh and Wh pulses directly through LEDs D20 and D3 respectively with an external optical probe. See following figure.
    Figure 3-24. Opto-Port for Pulse Output
  3. Isolated Pulse Output. The user can measure the VARh and Wh pulses with isolation on connectors, J25 and J24 respectively, in differential mode. See following figure.
    Figure 3-25. Isolated Pulse Output
  4. Relays control port for external purposes. The user can connect an external 3-phase latching relay and its power stage to the PL360MB board. For that, the following signal lines are routed to a 4-pin HE14 connector:
    • J26, pin 1: COIL_ON_CM – ON Command, microcontroller request
    • J26, pin 2: COIL_OFF_CMD – OFF Command, microcontroller request
    • J26, pin 3: POSITION_RELAY – Relay Status
    • J26, pin 4: GND – Digital Ground Reference
    By default, COIL_ON_CM and COIL_OFF_CMD are pulled down to Ground through a 10 kΩ resistor and POSITION_RELAY is pulled up to 3.3 volts through a 10 kΩ resistor. See following figure.
    Figure 3-26. Relay Control Port