Digital Output Pulse in Sequencer

Derek Demuth

Posted on 25.10.2016 13:14


I am trying to send a 50 ms pulse through a digital output to solid state relays and back into a Dewetron using Analog inputs. The test is over 4 minutes with an increment in pulses over 20 second gaps. I have the Orion 1616 card.

I set a calculation to turn on and off a digital output with a 50 ms delay in between each command. Looking at the Digital Output, the gap is commonly closer to 90 ms and the data will have random issues, appearing like a command was skipped at times. The analog in mimics the Digital Out very well. I have tried different sample rates and get the same random issues.

This may be a hardware issue, but the guys at Dewesoft are much more helpful, so I am just asking if there is a setting I am missing, or if I need longer pulse widths.

DEWESoft Support
Technical support
Posted on 27.10.2016 12:46


first of, thank you for the compliment. I've done a couple of tests between different software versions to see how they perform in combination with the same Sirius slice. Since you have an Orion card, I believe that you are a DEWESoft V7 user. In my tests DEWESoft V7 was outputting pluses according to your sequence with a pulse width of approximately 70 ms. In DEWESoft X2 I was able to narrow down the width to as close to 50 ms as possible (attached picture). The reason for this is the increase in performance. In X2, I am able to set the acquisition update rate to 1000 Hz, while V7 only allows me to go up to 10 ms (100 Hz). The calculations and the sequencer reaction time are also a bit quicker, which leads to faster responses. I would recommend that you set the acquisition update rate in your global settings to the lowest possible number and maybe also increase the software priority to real time. Hopefully this will decrease the length of your pulse widths. I haven't noticed any skipped cycles in my tests, so I'm not what could be wrong there. Are you receiving any errors with the missing pulses?

Attached files:
Derek Demuth

Posted on 28.10.2016 18:01

Thank you. I talked to support on the phone the other day, and they recommended using a reference curve and a formula, but I was still having issues. I read about settings, but usually went into hardware or project. My menus dont match the online help but I finally went into global settings and lowered acquisition update rate, set priority to realtime, and with using a reference curve I am getting the pulse width I need. I will write the sequence in excel and then post back if issues still exist. Thank you so much!! I spent so much time looking at the other settings, I should have dug harder.

DEWESoft Support
Technical support
Posted on 03.11.2016 07:53


it's no problem, thank you for the feedback. The settings have changed a bit between the old V7 and the new X2 version, so it can be a bit confusing. If you need specific help for V7, then I think the X1 manual is probably the best source. On the contrary, the PRO training is the best source of information for X2 and general application. The reference curve is a good idea because it's predefined and doesn't need to constantly wait for new inputs, which increases the delay/response time.

Good luck with your measurements.

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