Controlling Brushless maxon DC motrs using NI 6221 PCI Daq card

[venkata83]

Hi ,

I have a NI 6221 PCI Daq (M Series) card. I need to know how to use it to control a brushless DC motor from maxon with digital encoder? Also I need to know how to access the daq from matlab 7.0 as i am not familiar with labview and i need to know where i can get the matlab drivers for the card. Also i am trying to learn labview in the course of time. So it would be great if someone can give me some good tutorials in labview for motor control.

Thanks

Venkat

Venkat

Message Edited by venkata83 on 11-24-2005 03:30 PM

[venkata83]

We were planning to connect the encoder to the DAQ card to obtain feedback information and the outputs on the DAQ card to drive the different phases on the motor with a driver amplifier circuit. We are starting out in this area and wanted to know if such a setup would work for a closed loop control application for the motor.

Is it absolutely necessary to have a dedicated motion control card or is it possible to use the DAQ as a control device as well with an amplifier circuit thrown in.

[JB]

It will be very difficult if not impossible to drive the BLDC motor with a DAQ card! I would strongly suggest you to use an EPOS driver from maxon. You can communicate with the EPOS through CAN or serial communication.

[Jochen]

I strongly agree with JB that a DAQ board (especially if it is used under Windows) is not a recommended way to control a motor. A typical motion controller runs the trajectory generation, the control loop and other time critical tasks like limit switch detection in a real-time task.
Besides the EPOS driver from Maxon there are also PCI motion control boards available from NI for stepper and servo motor control.
NI motion control boards provide an easy to use API for LabVIEW and other IDEs and a tight integration to other measurement equipment like your NI 6221 through the RTSI bus.

Best regards,

Jochen Klier
National Instruments Germany

[venkata83]

Thanks for the replies.

I have decided to go in for PIC-SERVO SC 3PH Motion Control Board. I want to know whether we can interface the daq card with  the motion control board so that we can receive & transfer data at high speeds.

Venkat

[AnalogKid2DigitalMan]

According to the SC 3P specs it uses RS-485 (or RS-233 with specified converter), so no need for a DAQ card since it uses serial communications.

[venkata83]

I was wondering what the low cost options are for an integrated motion driver card which would be able to drive more than one brushless motor (looking towards the future) and at the same time be compatible with the 6221 Data acquisition card. Thanks for all the help so far, it has helped us immensely.

[Jochen]

The lowest cost servo control option from NI is the PCI-7342 board which allows you to control two servo motors.
Please have a look at the datasheet for a detailed description.
Both, the 6221 and the 7342 provide synchronisation capabilities through the internal RTSI-Bus interface. This makes it easy to correlate e. g. analog values and motor positions.
As the 7342 doesn't provide power you will need to connect the board to an external drive.

Jochen

[JB]

Hi Jochen,

Are you sure that the PCI-7342 will work with a BRUSHLESS DC motor ? I'm afraid not. You need a PCI-7352 motion controller.

Greetings

[Jochen]

Not necessarily. There are many drives available that do the commutation internally (e. g. Kollmorgen Servostar,...). That means the Hall sensor signals from the motor are only connected to the drive and the quadrature encoder signals for the 734x board are emulated by the drive.
If the drive doesn't do the commutation then the 735x boards are an option.

Jochen