Jump to content
  • 0

Power from the USB 2416


Mackenzie Cox

Question

13 answers to this question

Recommended Posts

  • 0

Hello Mackenzie,

The USB-2416 cannot be used to power sensors, instead you must provide it.  Could you let me know the make and model of the pressure sensor? If it's of the type I believe it is, you may need only one supply, such as +12 volts. 

Best regards,

Johhn

Link to comment
Share on other sites

  • 0

"DC voltage output transmitters connect using three wires—two wires into the power supply and a separate wire that sends a signal to the receiver. The receiver and the transmitter share a common ground wire back to the power supply."

The question then becomes, do you connect the power supply to the (+) & (-) pins or between GND & (+).  I believe you use the (+) & (-) for power. You cannot use anything less than +14 volts, but a +15, 18 or 24 volt power supply will work.

Connect the (Output) pin to the USB-2416 CH0H and the (-) pin to CH0L. Add a 100k ohm resistor from CH0L to GND on the USB-2416.  This is a differential connection and is preferred. You could also set the USB-2416 channel to single-ended mode. This may be easier because because all you must do is connect the Output to CH0H and the (-) to GND on the USB-2416. If you have long wires like six feet or more, use the first method because it will provide better noise rejection.

To scale the voltage reading to PSI, simply multiply the voltage reading by 10.

Best regards,

John

Link to comment
Share on other sites

  • 0

Okay, thank you that is very helpful. Do you have any insight on how to connect this soil moisture sensor as well? I may have to contact the supplier as the wiring diagram does not seem to match reality. There are two additional wires on mine that are not pictured here, but I would be curious to see if you knew how to connect this before I do that.
https://www.seeedstudio.com/RS485-Soil-Moisture-Temperature-Sensor-S-Soil-MT-02-p-4634.html

Link to comment
Share on other sites

  • 0

Your soil moisture sensor is not analog and instead it's a digital sensor that has a modbus RS485 interface. You will want to use something like this:https://www.amazon.com/Icstation-Resistive-Soil-Moisture-Sensor/dp/B076DDWDJK or this: https://wiki.dfrobot.com/Waterproof_Capacitive_Soil_Moisture_Sensor_SKU_SEN0308 both of which output an analog voltage for the moisture %. 

Best regards,
John

Link to comment
Share on other sites

  • 0

This sensor requires a device that can read the frequency of its square wave output. The USB-2416 does have a Counter input that could be used for this, but it would require the DASYLab software to measure frequency. Our basic software packages (DAQami & TracerDAQ) cannot. 

 

image.png

Link to comment
Share on other sites

  • 0

That would be best, but another option is to purchase DASYLab Lite ($499). It has the ability to convert the square wave flow sensor signal to a frequency measurement using the counter input. If you own LabVIEW you could use it too to make the measurement.

best regards,

John

Link to comment
Share on other sites

  • 0

The 2416 is isolated from ground and if the signal is also isolated, the measurement appears float - up in your case. So you need to provide it a reference point to make the measurement. 

Connect a 100k ohm resistor from the 2416 CH L input to GND. 

for example

image.png

The resistor provides a little bit of current as a path to ground but maintains the benefits of a differential input.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...