breakpoints are missing

[connector]

Hello:

I am using Modulus breakpoint(host re-enable). When the motor speed is higher, breakpoints are missing. Is there anyway we can do high speed DAQ and motion synchronization?

thanks a lot

[Jochen]

There is a lot of information missing in this question:

1. Type of motion board?
2. Type of DAQ board?
3. Type of measurement (AI, Counter, DI)?
4. Type of motor used?
5. Encoder feedback y/n?

I assume that you are using a PCI-7344 with servo motors and encoder feedback and you are using an NI DAQ board for analog input.

With the 7344 breakpoints need to be reenabled after each occurrence. This could either be done in an onboard program or on the host. In both cases the breakpoint frequency is limited to about 1 kHz. However the onboard solution is more deterministic than the host solution.

Whenever you need breakpoint rates higher than that you should either use the feedback signal as the scanclock for your DAQ board (routed via RTSI) or you could also use
a counter on the DAQ board as a prescaler of the feedback signal.

Another option is the use of the new PXI-7350 board that adds support for buffered breakpoints, buffered high-speed capture, and periodic breakpoints (4 MHz).

If you need more information please give me the information I've requested above.

Regards,

Jochen Klier
Applications Engineering Group Leader
National Instruments Germany GMbH

[connector]

Dear Jochen:

Thanks for your answer.

I am using PCI7344 motion board, PCI 6023E DAQ board, AI measurement, encoder feedback.

The freq of the measurement will be 3000Hz.

I really appreciate any further information on this.

Thanks and have a nice day

[Jochen]

In this case you should connect the 7344 and the 6023E via a RTSI cable and route the A or B encoder signal to the scanclock of the 6023E. In this case you will get position based analog input values with a velocity dependant sample rate.

With LabVIEW there ships an example called RTSI with DAQ (encoder-external scanclock).vi that works like that. Please tell me if you are not using LabVIEW.

If you want to use a non-varying sample frequency you should use one additional analog input to sample one or both encoder phases and do an offline data analysis.

Regards,

Jochen Klier
Applications Engineering Group Leader
National Instruments Germany GmbH

[connector]

Dear Jochen:

thanks a lot. I ordered the RTSI cable last week. I will give it a try.