@deltauser,
Thank you for attaching the DAQami configuration file. I was able to open the file, though I do not have any wires nor sensors connected to an USB-231. Did you create this configuration or was it part of the project given to you?
In DAQami, the Configuration Panel shows a Channel Mode set to Single-Ended, which allows a user to select any of the eight available analog input channels. For this configuration, analog input channels AI2 - AI5 are selected as Active.
Those channels represent the device's CH2 - CH5 channels. Below is an image of the USB-231 terminals for single-ended wiring, with those specific channels highlighted. (USB-231 User's Guide: https://files.digilent.com/manuals/USB-231.pdf)
You should be able to trace the physical wiring from these terminals to a source. Likewise, you can trace the signals connected to the two analog output channels and seven digital I/O channels.
Once you know where the wires are connected, the next step is figuring out how they are used. DAQami requires a user's interaction. When you press the green arrow button (or red circle button), the USB-231 device becomes active for acquiring data and controlling outputs (analog and digital). The 'ENABLE BOARD' channel (DIO5) is configured as an output channel. According to the digital output specification table #6, in the user's guide, the maximum output voltage from a digital channel is 3.6 V. Does this LVTTL signal control a circuit in your project? The label for analog output 0 (AOUT0) shows 'Status LED'. Is that line controlling your lights? Keep investigating the other wires.
With regards to your two sensors, SICK DT50-P1123 and LM35DZ, I was able to locate their data sheets.
https://cdn.sick.com/media/pdf/8/68/268/dataSheet_DT50-P1123_1047118_en.pdf
https://www.ti.com/lit/ds/symlink/lm35.pdf
Continue your investigation and keep us posted.
Regards,
Fausto
You are going to be successful if you know what your sensors output. The USB231 measures voltage. Your sensors may output voltage or current. You mentioned at the beginning that you have a distance sensor that outputs 4-20 milliamps (mA). Because we measure voltage, not current, we use a resistor to convert the current to a voltage. Many customers use a 250 ohm resistor because that results in a voltage between 1 & 5 volts. The USB-231 must be in differential mode to measure the voltage drop across the resistor.
Your sensor measures 0 - 200mm; at 200mm, the measurement is 5 volts (20mA * 250). At zero distance, the measurement is 1 volt. The scale factor is 200 / (5 - 1) or 25. The offset is 0 = 1 * (200 / (5-1)) + b, where b is the offset. Rearrange the equation, and you get b = -25. So the scale equation to get distance is f(x) = 25x - 25, where x is the measured voltage.
Here's a quick read on 4-20mA sensors https://digilent.com/reference/daq-and-datalogging/documents/current-sensors
It is up to you to modify the program to convert the voltage readings to something more meaningful, like temperature or distance. For example, a sensor rated at 100 with a 4-20mA (1 to 5 volt) output can be scaled by multiplying the voltage by 25 and subtracting 25, assuming you're using a 250 ohm shunt resistor.
