Is there anybody who has interface NI DAQ card with Pressure System Scanners

[Balaji_DP]

I am trying to acquire data from Pressure System's sensor ESP 16 BP with NI DAQ card PCI-6221.

Is there anybody who has perform this job.

Thanks,

Surender Kumar

[Brian F.]

Hello Surender. 

Thank you for contacting National Instruments. 

Although I have never used that particular pressure sensor, the setup for measuring a pressure sensor is usually the same.  Since the sensor probably outputs a voltage that is correlated with the amount of pressure that the sensor is detecting, we can configure a voltage task inside of Measurement and Automation Explorer and then port that into LabVIEW.  A great video tutorial of a DAQmx task being created and then transferred into LabVIEW is available at:

Creating a Task in NI-DAQmx and Using it in LabVIEW

http://zone.ni.com/devzone/cda/tut/p/id/5374#toc2

Also, there is a great site that contains general information on pressure sensors at:

Measuring Pressure with Pressure Sensors

http://zone.ni.com/devzone/cda/tut/p/id/3639

Let me know if this information answers your questions.  If you have a more specific question, please let us know and we would be happy to help you. 

Happy Holidays!

Brian F

Applications Engineer

National Instruments

[Balaji_DP]

Thanks Brian,

In these pressure sensors there are 4 digital inputs for selecting channels and only one analog output (binary selection).

My confusion is this how can i give micro second delay between channels while acquring signal , the analog o/p of sensor is only one and channel will be selected with digital lines and a microsecond delay is needed.

Regards

Surender Kumar

[Brian F.]

Hello Surender. 

If you desire to have a one ms delay between acquisitions on each channel, you could use the LabVIEW timing VI's to introduce this delay.

I am interested to know why you need to have this delay.  It would be less code intensive to simply acquire a set number of points on each channel and then switch to the next channel.  So, is there some reason why you need to have this ms delay between switching to each channel?  Relaying this information and more detailed information about the system could be useful for developing the most appropriate solution to your question. 

Brian F

Applications Engineer

National Instruments

[Ben]

Brian,

Can a PCI-6221 be configured to do an Analog acquisition which is clocked by the same source that clocks the on-board counters?

Can the counter lines be routed to DO lines?

If so that approach may be helpful here.

Otherwise a USB-cFP solution could do this in short order ... I guess

Ben

[Brian F.]

Hello Ben. 

Counter lines can be routed to DO lines using the DAQmx Connect Terminals VI which creates a static connection between two lines on the board.  However, since this is a static connection, the only way to disconnect these terminals is to use the DAQmx Disconnect Terminals VI or to reset the device.  A better way to accomplish this most times is to use the Export DAQmx Signal VI which allows the clocks onboard to be routed to RTSI and PFI lines. 

I think the best way to accomplish this is to use correlated DIO.  Correlated DIO enables digital and analog functions to be synchronized with hardware-timed precision, which will allow a pulse train of user defined frequency to be output and control the acquisition speed of the pressure sensor readings.  However, the success of Surender's application will be dependent on how quickly his particular sensor can switch between channels and take accurate readings.  I would recommend using a LabVIEW shipping example, Multi-Function-Synch Dig Read Write With Counter.vi, to get started with the correlated DIO aspect of his programming.

Brian F

Applications Engineer

National Instruments