In a robotics project and need an indicator to show the operator when the safety circuit is open or closed. Got it done in software but need a physical idiot light. Thinking a bright red/green bi-color led. Have 24 vdc constant supply and a pin that sinks to ground (100mA max) just while the door is closed. Can only use the channel on the I/O connector (the pin) as the signal for the open/closed condition. No additional switches or contacts and KISS would be greatly appreciated.