Displacement measurement with string pot

[davisjosek]

Hi, 

I have a 9178 chassis along with 9219, 9239, and 9236. I am trying to log some displacement values with a string pot with signal express. But in Signal Express, under displacement, it show only LVDTs and Eddy current proximity sensors as input. Is the only way I have around is to give an external excitation and measure the voltage from the string pot and manually convert it to displacement? Is there any way I can log the voltage from the string pot and get it converted to displacement by Signal Express. Will external exitation affect the acuracy of the measurement as the reference datum are different? The max internal exitation possible with the boards I have is only 3.3V. 

Also suggest me a NI board which can give exitation voltage up to 30V. I am using it for automotive application where I have to test up to 2X the rated voltage. 

Singal express is only showing LVDTs ad RVDTs for linear and angular displacement. Which NI board can support these? 

Thanks in advance. 

[PQM]

Hello davisjosek;

Can you tell what is the output signal of the string pot and also which of the mentioned modules are you using to connect the output signal of the sensor  ?

The 30 V exitation voltage board you need refers to a device that can provide a 30 V constant value ?  A digital signal from a externally powered module works ?

Let me know this information!

Warm Regards,

Pablo Quesada

[davisjosek]

the output from the string pot is voltage. 9219, 9239 and 9236 can measure, log and plot voltage. but i didnot see an option in signal express where i can define the limits and get the output as displacement. 

I need 12V continuous excitation and 30V peak for short duration of 2-3 seconds, and that is for testing some sensors. The control modules in automobiles supply filtered voltage supply to the sensors and the output is monitored against the same ground, for accurate measurement. So if i use an external source, i might not be able to simulate the same situation here. 

[PQM]

In the  Data Acquisition Assistant once you create the analog input  task for voltage you can  apply a custom scale for example Map Ranges for the voltage input  so you will be able to get the output of the sensor and read it as displacement. Did you try this ?

Regards,

Pablo Quesada

[Dennis_Knutson]

You should really post to the SignslExpress board. This is the LabVIEW board which you would use of you wanted to create your own application. Not many SignalExpress users here.