Motor RPm control using NI 9263

[vnarang]

Hi

I am Vikas Narang,I am stuck at one place from many days.Please help me.I am using NI 9263 to controll the RPM of a pum motor.I am actually able to vary the rpm.But,motor rpm are not going above 500.Then I checked the voltage signal at the pump end using multimeter.what i observed is the voltage signal at the pump end are not going above 3.6 V,even though I am increasing voltage from Measurment and Automation Labview to 10 Volts.

I refferd the motor manual,it says analog signal required for the motor is 0-10 V(dc)/0-20mA.

I believe NI 9263 has a range of ±10V and current produce by each module is 1 mA.Is this the problem.I mean current rrquired for the motor is 0-29mA but Ni is producing only 1 mA.

Please comment if I am thinking in the rite direction and if yes Please suggest me what shud I do to fix this.

I will be great full

[vnarang]

sorry I forgot to mention,Motot is an AC motor and there is some electronic circuit which I dont understand controls the rpm.and This electronic circuit needs  ± 10 V/0-20mA Analog input

[Greg_S-Video]

Hello Vikas

I believe this is likely the issue.  As per the specification, one channel on the NI 9263 will only output 1 mA of current as you.  Can you please tell me the manufacturer and model number for your pump motor?

You may be interested in some of our controllers and drives if you wish to achieve this functionality. 

Please consult the following link:

http://sine.ni.com/np/app/main/p/ap/motion/lang/en/pg/1/sn/n17:motion/fmid/112#h13

Please let me know if I can be of further assistance.  All the best!

[vnarang]

Hello Greg

Thanka s a lot for replying.I am a student at Michigan Tech.Due to limited research budget I may not be able to go for the prduct you mentioned.Iam sure this will be a great solution.But,I will be very greatfull to you if U can Please advise me something which involves less investmen,probably an amplifier and its configuration.

Appricate you help.

[Greg_S-Video]

Hello vnarang

Thank you for your response.  An inexpensive solution to this issue may be the use of a unity gain buffer.  Provided you purchase the correct operational amplifier with a current rating of at least 20 mA, this should be able to work with your system.

Here is some basic information on Unity Gain Buffers

The Unity Gain Buffer Amplifier - (a.k.a. The Isolation Amplifier)
http://www.facstaff.bucknell.edu/mastascu/elessonshtml/OpAmps/OpAmp3Note1Buffer.html

Here is one of our internal knowledge bases on how to implement a unity gain buffer with our DAQ devices.

Using a Unity Gain Buffer (Voltage Follower) with a DAQ Device
http://zone.ni.com/devzone/cda/tut/p/id/4494

Please let me know if you are able to accomplish this modification to your system.

[vnarang]

Hi Greg

Thanks a lot for your help.I have talked ot Cadeka for the amplifer U suggested.I will let U know  as soon as I hear from them

Thanks

[vnarang]

Hi Greg

Pump Manuf told me pump needs minimum of 5 mamp to drive, and NI 963 can only supply 1 mamp.I talked to lods of amplifer manufacturers about this but no success.Can U Please suggest me some manufacturer's specific product which I can buy?

Please

Thanks

Vikas

[vnarang]

Hi Greg

Pump Manuf told me pump needs minimum of 5 mamp to drive, and NI 963 can only supply 1 mamp.I talked to lods of amplifer manufacturers about this but no success.Can U Please suggest me some manufacturer's specific product which I can buy?

Please

Thanks

Vikas

[Greg_S-Video]

Hello Vikas

Do you have access to a standard LM741A Operartional Amplifier?  I'm certain one of your associates in another lab could probably provide you one.  From the specification sheet, it should be able to handle up to 25 mA and at least it would be a start for testing purposes in case you need something that delivers more current.  Please review the following information.

LM741A Operational Amplifier

http://www.national.com/ds/LM/LM741.pdf

How to read an op-amp data sheet:

http://www.physics.unlv.edu/~bill/PHYS483/op_amp_datasheet.pdf

Op Amps for Everyone

http://focus.ti.com/lit/an/slod006b/slod006b.pdf

If you can not find an associate who has one of these, you can certainly order them online.  I would suggest getting contact with your Electrical Engineering department's supply centre first.

Please let me know of your results!

[vnarang]

Hi Greg

Thanks for the help,I had a discussion with National Semiconductors abou this amplifer,all th amplifers they have suggested are ones which I have to put in my circuit.But I need external amplifers to which I can just connect my wires and start using it ,I dont have much exposure to these circuits.Please suggest

Regards

Vikas