Pulse oximeter probes connect to monitors via DB9 connectors carrying LED drive signals for red and infrared LEDs and the photodiode signal for SpO2 and pulse rate measurement.
| Pin | Name | Function | Type |
|---|---|---|---|
| 1 | LED_RED+ | Red LED 660nm anode | PWR |
| 2 | LED_IR+ | Infrared LED 940nm anode | PWR |
| 3 | LED_COM | LED common cathode | GND |
| 4 | PD+ | Photodiode signal positive | ADC |
| 5 | PD- | Photodiode signal negative or ground | GND |
| 6 | SHIELD | Cable shield | GND |
| 7 | ID | Probe type identification resistor | I/O |
| 8 | GND | Ground | GND |
| 9 | VCC | Probe supply voltage | PWR |
Pulse oximeter probes connect to monitors via DB9 connectors carrying LED drive signals for red and infrared LEDs and the photodiode signal for SpO2 and pulse rate measurement.