I have a Fieldpoint IO rack with only analog inputs available as spares. I want to use one of these analog voltage inputs sdimply as a on / off monitor for a 24VDC signal. Do I need to lower this voltage to say 10V or can I simply apply the 24V to the input without causing damage to the module?
The FP-AI-100 and FP-AI-102 have voltage ranges of ±30 V and ±120 V, respectively. However, the FP-AI-110 only has a maximum voltage range of ±10 V, so you would need to lower the voltage to be within this range to avoid damage to the module.
In the operating instructions, under the specifications, Voltage Inputs, it states that overvoltage protection is provided at +/-40V and the input impedance is over 100M Ohm. Additionally, I will be using 15V instead of 24V....are you certain that applying 15V will damage the input?
Input overvoltage protection is not intended to protect against a long term overvoltage condition. You should follow NI's advice and consider external voltage divider. Better yet would be an optoisolator circuit that would prevent coupling unwanted noise into your analog module.