Recommended module for cDAQ (Position Transducer)

[nssid]

Hi,

I have the NI 9237 module that I use with the cDAQ (NI - 9178) to measure Strains. I now need a module with cDAQ compatibility to use with a position Transducer. The specs of the position transducer (Novotechnik TR100) can be found here. If you take a look at the specs, you will see that the max permissible applied voltage is 42 V. So, it looks like the transducer is actually a potentiometer (correct me if I am wrong). Is there any recommended module that I can use with my transducer ? 

Thanks,

Sid

[NathanS]

Hi Sid,

After looking at the specs of your transducer, I lean toward recommending you take a look at the NI-9219, in the 10kOhm range for 2-wire resistance measurements, although I admit that I am not super familiar with the transducer you are using, so you will want to check the spec ranges just to make sure that's appropriate. Hope that helps!

Regards,

[nssid]

Hello Nathan,

Thanks for your reply. The 9219 looks like it will work. However I just want to clarify something. My sensor (the potentiometer) has three wires coming out (Power, Signal and Ground). I just looked into signal names and terminals table in the NI 9219 manual. Do you think I can connect my Ground to terminal 5, Power to terminal 3 and Signal to terminal 4 ?

Thanks,

Sid

[NathanS]

Hi Sid,

It seems to me that you want to follow the 2-Wire Resistance row in the Terminals table, which says:

2-Wire Resistance:
T+ Terminal 1
T– Terminal 2
HI Terminal 3
LO Terminal 5

I'm not sure which of those signals corresponds to which wire on your potentiometer, just because I'm not familiar with that transducer. You might want to contact the manufacturer to confirm that. It would seem to me that if you have Power, Signal, and Ground, then you would want to connect them like this:

HI - Signal
LO - Ground
T+ - Power

That would be my best guess, but I could easily be wrong. Again, I am not familiar with that transducer so don't quote me on it please.

Regards,

[nssid]

Just to clarify something. What does the "TEDS data" and the "TEDS COM" mean ? Are these terminals for power/excitation ?

[AnalogKid2DigitalMan]

The TEDS connection are for "smart" sensors than can communicate with module to automatically provide identification, scaling, and calibration info to the system.

Not used for your potentiometer.

-AK2DM

[nssid]

AK2DM,

So where do I  connect my power line from my potentiometer on the 9219 then ? Should I use the 3 wire RTD mode shown in the manual ? (What does RTD stand for ?)

Sid

[nssid]

Also, the manual says

"Use the excitation terminals if the sensor requires a separate excitation connection. Refer to the NI 9219 Circuitry section for information about
connections in each mode. " The circuit provided is

So, doesnt this mean that the excitation terminals are T+ and T- ?

I am new in using DAQ's and sensors and correct me if I am wrong any where. I appreciate your help.

[AnalogKid2DigitalMan]

Wow! Just had a look at the manual for the 9219 device- pretty darn versatile.

OK- You want to refer to Fig 10 in the manual- 2 wire resistance. Depending on how you want your resistance to increase/decrease depending on direction of travel, connect either (pins 1 and 2

OR pins 3 and 2) to the HI (3) and LO (5) on the 9219. Refer to Table 2 for 2 wire resistance.

The 9219 has a built in current source to measure resistance thus you do not need to make any voltage connections to your potentiometer.

The 9219 has 1K and 10K ranges, so select that accordingly to match the resistance of your potentiometer.

RTD = Resistance Temperature Detector- it varies its resistance based on temperature.

Hope this helps!

-AK2DM

[nssid]

Perfect ! That answers my question. Thanks !!