I am new to LabVIEW, I am trying to connect an NPN inductive proximity sensor to the NI CompactRIO chassis (cRIO-9014). My understanding is that the proximity sensor would give out a digital signal. I have access to the NI9401 module. Can I use a NI 9923 connector to connect the sensor or do I have to get the NI9422 module? The ratings of the sensor are as follows:
Contrinex, NPN NO Embeddable
Input voltage: 10 - 30 VDC
I also have access to an Agilent 6682A power supply which I can use for the source.
Also, while connecting the sensor should I use resistors in between the source and sensor. It would be great if someone could help out with the circuit diagram as well.
First we have a look into the datasheets: (Bonuspoint for your question, you provided a link 🙂 )
and of the NI9401
the sensor needs a 10V (min) supply, that's more than the spec of the DI input want to see 😉
so yes, you need a resisitor and to be kind to the DI some sort of voltage limiting in the range of 2-5 V.
Voltage limiting in this case could be 3-5 diodes (1N4148 or 400x or ) each good for ~ 0.7V or a z-diode with 3-5V or (my choice) 1-2 LEDs, number depend on the forward voltage, a typical blue one has 2,7 to 3,5V perfect 🙂
Since you need a external supply for the sensor anyway with 10-30 V ,
+ supply to PIN 1
- supply to PIN3 and COM.
the resistor goes from + supply (and PIN 1) to the PIN 4
the LED (or other diodes) goes from PIN 4 to PIN 3 (+COM)
PIN 4 (+R+LED) to the DI
The value of the resistor limits the current . 10k Ohm is a good value. Pin 4 (the NPN output , that shortens the pin 4 to pin 3 (- supply and COM) ) also connects to the DI.
(DI for DIOx of 9401)
Before you connect the sensor with the resistor and LED to the 9401, it's a good idea to check the voltages with a multimeter.
Not activ the LED should lit and you should measure a voltage in the range of 2-5 V. With the sensor active the LED should turn off and the voltage should be below 0.8 (better 0.3) V , I expect nearly zero 😉
Another way with just one resistor (4.7-10k) would need one of your DIOs to be configured as an output to source 5V .. see schematic of DIO1 in the fig. . The switch is pin 4 and pin 3 of your sensor. But another 'Hello World' and a free DIO is worth a LED 😄