Greetings,

I am currently configuring a soil pressure transducer from Tokyo Measuring Instruments with a DT80 Series 4 data logger. I have calibration data (attached images) but am having trouble setting the DEX-2 parameters for the sensor based on these documents.

I am using a Current Bridge but am unsure what the channel variable should be or what to assign it to. The input range is set to Auto range (30 mv to 3V), with an arm resistance of 350Ω and a default excitation of 2.5 mA.

For the span, I have attempted various voltage-to-MPa relationships but have not achieved a readable value.

Would it be possible to get assistance with this configuration? Any feedback would be greatly appreciated.

Thank you!

Hi Daniela23,

You can refer to the wiring (second picture), red goes to *, black to #, white to + and green to -. You can connect the shield to D GND pin.

After you get the wiring correct:

• If you are using BGI, you can check the sensor resistance (first page). Because there are two values 352.1 and 352.7, you can get the average which is 352.4 ohms. Assuming you use terminal 1, then the syntax would be 1BGI(4W,352.4). If you are using dEX software, you can use 350 ohms.

1BGI(4W,352.4)

• If you are using BGV and getting the 4.5V excitation from the logger, you do not need to look the sensor resistance, the syntax would be

1+V(BR,2,V,W) 
1BGV

After you manage to secure the wiring and syntax, it is time for you to make conversion to the target unit. The dataTaker will provide you with ppm output which you must convert it to pressure (MPa).

The best would be using the rated output of +629 uV/V. Because the unit already in uV/V, you can multiply the ppm result to the rated output. Assuming you allocate 1CV and use current bridge:

1BGI(4W,350,=1CV)
2CV("Pressure~MPa")=1CV*629

As an extra, this type of sensor does not start from 0 MPa, so it would be best to take the initial reading (without any pressure applied) as a zero reference. You can substract the subsequent reading with that zero reference to get the actual pressure.

BEGIN"EXAMPLE"
  1BGI("ZeroRef",4W,350,=9CV,W)

RA1M LOGONA
  1BGI("RawPressure~MPa",4W,350,=1CV,W)
  2CV("Pressure~MPa")=(1CV-9CV)*629

END

Best regards,
dataTaker Expert

Thank you very much for your help. I would like to integrate this code into the DEX-2 software, but I am encountering some challenges. Is it possible to achieve this configuration solely using the DEX-2 interface, or do I need additional tools for coding the pressure cell setup?

The initial reading without any span is 554 ppm, I tried to create a dxt file to insert with the accurate operations but failed to upload the file to the software. The option to load from a file is not available (Why does this happen? In other computers this option is available). Additionally, I am unable to set the initial reading value to zero through a subtraction within the DEX-2 interface.

Initially, I assumed that adjusting the span would be sufficient, but this does not allow me to set the initial reading to zero and I cannot know what the maximum value the data taker reads in ppm to than convert to MPa.

I appreciate your guidance.
Best regards,

Hi Daniela23,

It is possible to recreate the script program in dEX 2.0. You can follow this step:

• Create a BGI channel by clicking + sign after "On Activation", this channel will serve as ZeroRef.
• Create a schedule by clicking + sign inside a circle after SCHEDULE. You can set the schedule interval here.
• Create a BGI channel by clicking + sign after the newly created schedule, this channel will serve as RawPressure.
• Create a calculation channel by clicking + sign after the newly created schedule. Set the subtraction between RawPressure and ZeroRef to obtain Pressure.

Notes:
You cannot load our previous script even after you save it into a file because the script is not following the default template of dEX 2.0.

Best regards,
dataTaker Expert