7344 RTOS speed performance

[WillieK]

I appear to get a better cycle time running my application by sending flexmotion commands to the 7344, instead of downloading the commands to the RTOS and running it there.
Is this possible?.....I am running basically the same commands, in fact I got rid of continuously loading the velocity and Acceleration data from the RTOS, and it still runs slower.

My application is stepper motion 500 counts (openloop) 50 times at high speed.

Where can I find the clock speed of the RTOS, and individual command clock cycle times.

Regards,

[PNHorn]

Hi Willie,

Sorry for the delay in answering this thread. I have been looking into this issue for you and have a couple of questions for you.

When you say downloading the commands to the RTOS, are you referring to onboard programs on the motion controller or running the code in LabVIEW RT?

For onboard programs, it is definitely possible for commands to run slower than when run from the host PC. This is mainly because the onboard program has the lowest priority of all tasks running on the MC68331microprocessor. Each onboard program only has a 2ms time-slice of the processor. After that 2ms, the processor is freed for housekeeping or other onboard tasks. Not only this, but all host communications (reading position, setting velocity, etc..) and all I/O re
actions (such as feedback) are given higher priority than the onboard program.

Hope this helps,

Best regards,

Peter H.
Applications Engineer.
National Instruments UK.

[WillieK]

OK, this answers my question. I was referring to Onboard programs, when I mentioned RTOS.

I was hoping to get better speed, and get rid of PC latency with the Onboard program, but this may not be the case with a 2ms slice.

Regards,