Why the max. velocity of PCI7358 is 8MPPS?

[Z257J]

Hi,

I'm quite confused about this Spec stated under "Stepper Performance" in "NI 7350 User Manual" Is it because of hardware limitation or due to my incorrect understanding?

Here's my understanding:

Vmax = 65535(pulse/sample) X (1/Ts)(sample/sec) 

           =

[Z257J]

Sorry wrong operation. Please delete the previous message.

Hi,

I'm quite confused about this Spec stated under "Stepper Performance" in "NI 7350 User Manual"       Is it because of hardware limitation or due to my incorrect understanding?

Here's my understanding:

Vmax = 65535(pulse/sample) X (1/Ts)(sample/sec) 

           = 65535 X 1/62.5 X 1000000

           = 1048560000(PPS)            // assume only one axis activated

The value is not improtant I just want to verify is my understanding correct or not. Thanks.

[JesseD]

Hello,

The maximum velocity is limited to the maximum frequency that can be generated on the stepper output.  In the case of the 7350 series boards, the hardware can generate a pulse up to 8 MHz (page A-3 of the "NI 7350 User Manual").  Thus, the max velocity we can achieve is 8,000,000 steps per second.

Regards,

Jesse D.

Applications Engineering

National Instruments

[Buechsenschuetz]

Whatever the reason for the max step frequency is, you will not find any motor or any drive which will accept more than 5 or 10 p.c. of the max step frequency possible with NI controllers.

Many motor drivers are PWM controlled and use an internal PWM frequency in the range of hundreds of kHz. The max step frequency of such drivers is just a fraction of their PWM frequency and in the range of 10s of kHz.