How to connect ni-9220 to clamp force sensor

[jin00]

Hello, I'm trying to measure force using a clamp with a built-in force sensor (K1463).

I used NI-max to verify that the clamp was working properly, but I think there was something wrong with the clamp circuit. The attached pictures show the pin configuration of the clamp and the circuit I am thinking of.

The clamp has a 4-20mA output range and measure analog current data using the NI-9220.

The clamp requires 10-30V DC power, and I'm using a power supply to meet the power requirements.

Any help in this regard is appreciated. Thanks in advance for your time!

pinout of the clamp

expected circuit

[santo_13]

The problem is that 9220 is a voltage input module, whereas your sensor seems to output current, so you missed converting the current output of the sensor to voltage for the module to read.

You can do this using a resistor connected across AI+ and AI- of the channels connected to the sensor.

Since 9220 supports +/-10V range, you can convert the 4-20mA to 2-10V range using a 500ohm resistor (accuracy of this resistance also determines your overall measurement accuracy).

[jin00]

Hi, santo

I didn't quite understand the part where you said "a resistor connected across AI+ and AI- of the channels connected to the sensor". So I connected a resistor in series between the sensor signal pin and the AI+ of the 9220. 

I would appreciate it if you could explain the resistor connection part in more detail.

Since I didn't have a 500 ohm resistor, I tried connecting a 300 ohm resistor instead. It should output 1.2 - 6V, but I'm getting completely different numbers.

Since 10V power is supplied through the power supply and 10V output is displayed, there is a possibility that the sensor circuit is faulty.

Thank you for your kind reply.

[santo_13 · Accepted solution]

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@jin00 wrote:

Hi, santo

I didn't quite understand the part where you said "a resistor connected across AI+ and AI- of the channels connected to the sensor". So I connected a resistor in series between the sensor signal pin and the AI+ of the 9220. 

I would appreciate it if you could explain the resistor connection part in more detail.

Since I didn't have a 500 ohm resistor, I tried connecting a 300 ohm resistor instead. It should output 1.2 - 6V, but I'm getting completely different numbers.

Since 10V power is supplied through the power supply and 10V output is displayed, there is a possibility that the sensor circuit is faulty.

Thank you for your kind reply.

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Yeah, 300ohm also works, just that you're not maximizing the usage of voltage input range for better resolution.

Connect the resistor as shown below, between AI+ and AI- i.e., as a load for the Sensor output.