8255R Pulse Generator Frequency Change

[djack]

Hi All,

First off, sorry if this is the wrong forum, but it's the closest I could find.

My question is....  

Is it possible to change the frequency of a continious pulse train after it has started?

I know I could Dispose of the PulseID and re-create it but that takes too long. I want to use the generated frequency to drive a sepper motor so the change in grequency should be smooth.

Thanks In Advance

DJack

[AdnanZ]

Hi DJack,

I hope you are doing well today! You are in the right forum. Actually, you should have just searched for your query in this forum and you would have got a reply. Have you looked at the following knowledge base article. It should have an answer for both, Traditional DAQ and DAQmx:
AE KB 2VIEAM6I: How Do I Change The Frequency Output Of My Pulse Train On The Fly?

[djack]

Hi Adnan,

Sorry, but this is not what I was looking for.

I should have been more specific in the original post, my fault, so please let me clarify:-

First, I'm using the PCiE 8255R combined 1394 capture and IO board.

Second, I'm using C++ to create my application on a WinXP platform.

Third, the only functions availible in the published IMAQ IO C Ref.chm help manual are:-  Create, Start, Stop and Dispose.

I can't see any other way of changing the frequency on the fly unless I can talk to the board at IO level.

Thanks Again for the reply.

Derek

[AdnanZ]

Hi Derek,

Sorry to misinterpret you. You are right; we don't have functions for this in our IMAQ driver. Good luck with your application!

[djack]

Hi Adnan

Is there any plan to impliment this in the future, maybe in the "imaqIOSetAttribute" function?

Without this functionality I doubt that I'll be able to use the 8255R board in my project.

Thanks again,

DJ

[AdnanZ]

Hi DJ,

I hope you are doing well today! I am not sure if this will be implemented in the future. However, I suggest you file a product suggestion at the Product Suggestion Center. That will definitely help in getting it noticed in R&D.

Behind the digital I/O of the NI 8255R is an FPGA which has been preconfigured with the functionality required for most common machine vision tasks. However, if the factory configured functionality does not fulfill your requirements, the FPGA is user-configurable with the LabVIEW FPGA Module. RIO allows you to develop custom FPGA logic to add triggering, pulse-width modulation signals, or custom communications protocols to your machine vision application.

Using National Instruments RIO hardware and the LabVIEW FPGA Module, you can define your hardware without in-depth knowledge of hardware design tools or hardware description languages (HDL). When the signal requirements change, the LabVIEW code can be modified and downloaded to the FPGA to change the I/O mix or type. This flexibility allows you to reuse the same hardware and software at no extra expense.

The the NI 8255R has 29 digital I/O lines with built-in functionality for communicating with external devices, such as reading quadrature encoder inputs, generating strobe pulses, and writing to or reading from digital lines. NI-IMAQ I/O devices have 15 digital input lines—13 optically isolated lines and two dedicated TTL lines. There are 14 digital output lines—four optically isolated lines and 10 dedicated TTL lines. Using these signals, you can dynamically control your lighting or cameras, synchronize with a conveyor belt, or communicate with relays that control solenoids and other actuators.

For more information about using the LabVIEW FPGA Module to implement custom FPGA logic, refer to the examples at <LabVIEW>\examples\IMAQ\IMAQ IO FPGA.llb.

If you have any other questions, please be sure to let us know.