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Is there a way to preset the cFP-QUAD-510 module?

Using MAX, there is a way to reset the cFP-QUAD-510 to zero.  However, is there a way to preset the counter programatically through LabVIEW to count values other than zero?
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Message 1 of 10
Hello dj143,

Please take a look at the following Knowledge Base on our website that discusses how to do this in LabWindows/CVI:

How Do I Reset the Counter on My FP-QUAD-510 Module Using LabWindows/CVI?

Though this KB is specifically targetted towards implementation in CVI, you can use the same procedure for LabVIEW.  Once you have the I/O Point configured for the Reset Control in MAX, you can use the FP Write VI in LabVIEW to write a '1' to this channel. 

Hope this helps!

Best regards,
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Message 2 of 10
This example can only reset the counter to zero; unless I'm missing something.  Is there a way to programmatically set the counter to a number other than zero as a "preset" value?
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Message 3 of 10
You are correct.  The method described in that KB can only reset the counter to zero.  Sorry I misunderstood your original post.  Unfortunately, there is no way to set the count value to anything other than zero, programmatically or otherwise.  I am wondering why you need to do this.  If you could give some description of your application, perhaps we can see if there's another way to approach the problem.

Best regards,
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Message 4 of 10

The application involves winch monitoring of cable payout and inhaul operations.  The end user may need to adjust the amount of cable paid out where it is impractical to place the winch in a "zero" position.  I'm programming the system with an offset so that the operator thinks the payout is being adjusted.  The lack of a counter preset function is not a show stopper.

I would think however that the cFP-QUAD-510 would have the ability to be preset because it would often be used for positioning systems.

I tell you what I really wish; is that the cFP-QUAD-510 had inputs and outputs like the cFP-CTR-50x counters.  This way I could use the QUAD for very low frequency measurements.  As it is, I have to use a QUAD for quadrature signals and a CTR for velocity measurements simultaneously in the same system.  This is an extra expense and hassle.

Thank you for responding.

Dave J.

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Message 5 of 10

Thanks for the information.  I first wanted to clarify that the cFP-QUAD-510 can be used for velocity measurements.  This is described in more detail in the FP-QUAD-510 and cFP-QUAD-510 Operating Instructions under the section Configuring [c]FP-QUAD-510 Channels >> Configuring Velocity Data Channels.  Is there a reason that this particular method of velocity measurement does not work for your application? 

As far as the counter preset function that you would like to see, please feel free to go to Contact NI and click on the feedback link to submit a product suggestion.  This feedback is looked at by R&D and taken under serious consideration when they are developing new products. 

Please let us know if you have any further questions about the cFP-QUAD-510. 

Best regards,
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Message 6 of 10
I need to monitor very low frequencies, i.e. 1 to 50 Hz.  The time base provided by the QUAD version is much too short.
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Message 7 of 10

With the 1-50 Hz range that you are trying to measure, you are correct in your assessment that the CTR-502 module would provide a more accurate reading.  Just for everyone's benefit, let me give a quick explaination of why this is. 

The QUAD-510 module has only eight allowable timebase settings for velocity measurements.  The timebase is essentially the "window" over which your quadrature encoder signal pulses are counted, and is equivalent to the gate signal that is used when doing frequency measurements with the CTR-502.  The longest window that can be applied with the QUAD-510 is 26,214.4 us, which results in a velocity resolution (accuracy) of 38.15 counts/s or 38.15 Hz.  As such, when trying to measure frequencies in the range of 1-50 Hz, your accuracy will be very low.

The CTR-502, on the other hand, can get much more accurate measurements at this frequency range because you can configure a much longer window.  There is a LabVIEW example that installs with the FieldPoint driver called "Frequency" that shows how to do frequency measurements with the CTR-502. 

Dave, if you would like to see better resolution for low frequency measurements with the QUAD-510, again, please feel free to submit a product suggestion for this functionality.  For now it sounds like you have the best hardware setup for your application.  I hope that the information I have provided has been helpful. 

Best regards,
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Message 8 of 10

Will the cFP-CTR-502 handle the Line Driver Outputs from an encoder and be used to calculate the frequency of one line?

I have a similar requirement and have posted about the 510 recently to make sure I understood the limitations of the velocity resolution.  Unfortunately the customer already purchased very low PPR encoders.  the QUAD-510 probably would have worked great if they went with 2500 PPR or higher encoders, but for some reason they went with 60 PPR before consulting us...

This leads me to looking into alternate methods to get the velocity from their encoder signals - and fequency measurements of the digital signal from one channel is fine for me (no direction changes) - but I am not sure the 5V Line Drive Output from the Encoder is compatible with the Sourcing inputs of the CTR-502.  Can anyone shed some light on that?

Ryan Vallieu CLA, CLED
Senior Systems Analyst II
NASA Ames Research Center
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Message 9 of 10
Hi Ryan,
You are correct. The CTR-502 cannot sink the output of your customer's encoders. You could create a circuit in between the encoder and the ctr module that would convert the outputs. For instance, use a common emitter set up of a transistor gated by the encoder's sourcing output to collect the sourcing output of the ctr module.
Maybe someone else will have an idea as well.
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Message 10 of 10