brushless motors with NI 7342

[mtrifo]

The "getting started with NI Motion Control" doc. deals only with brushed servo motors, and refers to the 7350 Hardware Manual for brushless servo motors. Does this mean that the 7342 motion controller is not suitable for brushless motor drivers ?

[Rodj]

mtrifo,

The NI-735x family of motion controllers can do the required sinusoidal commutation required for brushless motors. This allows you to use a less expensive drive. It also reduces your effective axis count in half since each axis requires two DACS now. You can still use all your axes if you operate half of them in stepper mode.

The NI-735x and NI-734x family of motion controllers can connect to brushless motors through a drive that does the sinusoidal commutation. The cost difference between a drive that does the sinusoidal commutation and one that doesn't is around a few hundred dollars I believe.

Rodger S.

[Jochen]

You can use the 7342 also for brushless motors but you need an "intelligent" drive then that does the electronic commutation by acquiring the hall sensor signals and calculating and generating the appropriate sine/cosine power signals for the motors then. There are plenty of these drives available from various vendors.

When you use the 7350 you can use a much less sophisticated drive as the electronic commutation is done by the 7350 in this case. Please note that if you use electronic commutation with 7350 boards the number of axes is divided by two (e. g. the 7354 can drive two brushless servo axes or four brushed servo axes) as you need two analog outputs per axis.

Best regards,

Jochen Klier
National Instruments Germany

[mtrifo]

Thanks you very much for the clarifications. Now I know what I have to check with our manufacturer about the capabilities of the motor driver we have to interfaces using the NI boards. As far as I know, the driver is interfaced through the 10V line, hence I guess it does the sinusoidal commutation, and the NI 7342 should be suitable.
Best Regards.