analog input of UMI-7764 and PCI-7330

[labmaster]

A commercial controller used UMI-7764 and PCI-7330 to control a motor.

In UMI-7764 (very old board of 1999), there are 4 analog input port.

Unfortunately, I couldn't find the AI channels in the Measurement Explorer of Labview.

In this case how can I use DAQmx function (that is, channel name)?

Attachment shows the error of PCI-7330.

How to remove the error icon in the Measurement explorer?

메시지가 07-07-2008 01:16 AM에 labmaster에 의해 편집되었음

[Jochen]

Hi,

the PCI-7330 has 4 analog inputs which are available through the UMI-7764 connector block. The hardware driver for the PCI-7330 is NI-Motion, so you can access these analog inputs through the NI-Motion API, which has nothing to do with NI-DAQmx.

The main purpose of the analog inputs on motion control boards is using them as analog feedback (e. g. to control a force) or to stop an axis if a limit (e. g. torque) is exceeded. You can use them for very simple measurement tasks, too, but you shouldn't expect a high level of accuracy (AIs on a 7330 are not calibrated; no preamplifier is implemented). Also you can use these AIs only in quite slow software polled mode (no hardware timing).

If these restrictions are ok for you, you can use the NI-Motion function calls "Enable ADC.flx", "Set ADC Range.flx" and "Read ADC.flx". Otherwise better use an M-Series device for your measurement task. The functions mentioned are LabVIEW functions. For other programming languages the function names are very similar. Please refer to the NI-Motion manuals if needed.

Kind regards,

Jochen Klier
National Instruments

[labmaster]

Thanks Jochen,

I need more short detail on your reply.

It will be helpful to understand the basic concepts.

Would you please explain me shortly about the calibration function of DAQmx different to PCI-7330?

(I want to decide the suitability of the old DAQ card.)

"slow software polled mode" means something similar with "1 channel 1 reading" of DAQmx function ?

What is the meaning of extension of "*.flx"?

Regards,

labmaster

[Jochen]

Hi labmaster,

I have added my answers to your questions.

Kind regards,
Jochen

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@labmaster wrote:

Thanks Jochen,

I need more short detail on your reply.

It will be helpful to understand the basic concepts.

Would you please explain me shortly about the calibration function of DAQmx different to PCI-7330?

(I want to decide the suitability of the old DAQ card.)
This answer is quite simple: The ADC input circuitry of a 7330 can't be calibrated at all, while the calibration algorithm for M-Series boards is highly sophisticated to guarantee a high level of accuracy. The accuracy of the 7330's ADC is not specified.

"slow software polled mode" means something similar with "1 channel 1 reading" of DAQmx function ?
Yes, that's comparable to some degree. The main difference here is the fact, that DAQmx can access the ADC data directly, while NI-Motion polls the CPU on the motion control board. This adds significantly more delay and jitter, but again: The ADCs on a motion control board are not designed for measurement tasks, so this is expected behavior.

What is the meaning of extension of "*.flx"?
This is in fact an anachronism. Initially NI-Motion wasn't developed by NI, but by NuLogic and this company has decided for some reason not to use the .vi extension for their vis, but .flx. NI has continued to use this extension for compatibility reasons.

Regards,

labmaster

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