Voltage level detection using DIO card

[GE_Osmonics]

Looking for a simple circuit to implement a 24 VDC voltage level detector using a DIO card

Thank You!

[AnalogKid2DigitalMan]

You could use a resistor based voltage divider to scale the 24V down to 5V TTL level that the card should accept. Does the 24V drop all the way to 0V when the signal is off?

[GE_Osmonics]

Yes, the voltage drop to 0. 

Thank you!

[AnalogKid2DigitalMan]

Excellent! The easiest example of a divider would be to use a 19Kohm in series with a 5Kohm resistor. One end of the 19K to the 24V signal, the other end to the 5K, the opposite end of the 5K to ground. Wire the ends of the 5K to the DIO inputs (input line and ground). This arrangement only draws 0.001A from the 24V signal.