How do I send multiple synchronous digital signals across individual lines?

[Jordan F]

Hi Hitesh,

1. No, th 6602 will not be able to acheive 1kHz rate because it does not have correlated digital input and output.  What this means is that the software determines the value of the line state.  So, if other tasks are running at the same time this will delay the update rate of the digital output.  It can not only not get the rate but it also is not deterministic. 

2. No, the 6602 has software timed update rates to there is no way to have full synchronization.  To acheive synchronization you need to have a shared clock (6602 does not have correlated DIO or a Digital Sample Clock) and a trigger. 

3. Either device will perform for this application.  There is going to be vast differences in development so it is up to you whether you want to learn how to program using the HSDIO driver or FPGA.  The FPGA may provide more outputs than HSDIO devices but the HSDIO cards can be synchronized easily for channel expansion. 

Regards,

[Hitesh_Dhola]

Hi jordan,

HSDIO is easy to handle... I have worked with HSDIO earlier... So, if we go for HSDIO.. Can it support PWM output ? My requirement is just to generate 80 PWM outputs with delakly introduced.

Each output in FPGA module can be treated as a PWM. in HSDIO is it possible ? 

Thanks

Hitesh Dhola 

[Jordan F]

Hi Hitesh,

I am not as familiar with FPGA as I am with HSDIO.  To make a change to the frequency or duty cycle, you need to change the waveform being generated.  There is only one clock for generation tasks so all of the channels are going to be updated at the same time.  You could stream a new waveform or use scripting to change the frequency or duty cycle. 

We do have built in data delay for HSDIO but this would not work for your application because you can only have one data delay value specified (you need it on every channel).  So, you would need to build your waveforms to account for this delay (pad the beginning of your waveforms with Z's or X's.  Depending on your clock rate, you could reach the delay resolution needed.

Regards,

[Hitesh_Dhola]

Hi Jordan,

You mean to say , In HSDIO, there is no function which directly changes frequency or Pulse width or delay. I have to generate waveform using boolean array. ?

That would be a problem then, My application is critical in nature. It's High voltage power supply, which has many small modules. According to requirement I want to turn on some Modules and average output will be final output of Power supply. When My load changes it should change immediately. So, I can not take risk of the delay introduced because of the calculation required to generate waveform (Boolean array) according to my frequency, pulse width and delay. That parameters would be changing very frequently and response should be very fast and accurate otherwise very high voltage spike or glitch may be generated.

FPGA has direct configuration of on time and offtime and delay, it can work as PWM according to input voltage (with little bit of calculations). I would prefer HSDIO more, because I am familiar with it and do not want to waste time in changing environment , but I think FPGA would suit application more.

What is your  opinion now ? Please let me know if you know more detail. It will help me.

---

Hitesh Dhola

[srm@viewpointusa.com]

With the current description of your application, i would definitely go with the FPGA solution.  while you are changing environments, I think you will find the explicit control of your application worth it.

[Jordan F]

I would recommend to go with the FPGA solution.  HSDIO is not able to perform the PWM that is required for your application.  You can change the frequency and offset of signals with HSDIO but it is limited in that you have to change the waveform to achieve this (scripting, streaming, etc.). So, to get the exact specifications, it would be recommended to use an FPGA.

Regards,

Jordan  

[Hitesh_Dhola]

Hi jordan,

I have tried to generate PWM signals using HSDIO 6542. It's generating waveform but, when i update waveform it gives error.

 can you tell me the problem.

[Hitesh_Dhola]

Is it must to use streaming or scripting for continuous generation of the waveform? 

Examples available for HSDIO in labview do not work on my system. can anyone suggest a topic, tutorial or examples. 

I have tried something else also using streaming , but not working.

Error is like : You should decrease the sample rate or waveform is not updated fast enough 

 

Where am I mistaking  ?

[Doug_L._Bear]

I agree with Jordan in the FPGA would give you better control over your application.  I would take a look at the following example available on the community at ni.com/community.  This example involves both scripting so that you can change your pulse width as you said you would like and also shows off TClk for synchronization which I blieve was another one of your requirements.

https://forums.ni.com/t5/Example-Code/Scripted-HSDIO-Synchronized-with-NI-TClk/ta-p/3504386

[Steve_B]

Doug's idea of working from an example to verify the functionality of the hardware is a good one. It will be easier to work with one of the examples and get something up and running. Regarding your code, it would be helpful to see the error and a description of some of the subVIs would be good, as well as your settings. My recommendation at this point would be to lower the sample rate if that is the error you are getting, I would continue to do so until the error goes away and work back from there. 

Are you building the entire waveform before hand and generating it from the HSDIO board? The final application seems to be best suited for an FPGA for the additional control that you need.