I Cannot Reach the Maximum Output Frequency Using NI 9403

Updated Jun 7, 2018

Reported In

Hardware

  • CompactRIO Chassis
  • NI-9403

Software

  • LabVIEW FPGA Module
  • LabVIEW

Issue Details

I'm using an NI 9403 in FPGA mode and I'm trying to generate a 70 KHz square wave.
I'm using to channels and I can reach 50 KHz, if I add any channel the maximum frequency decrease.
In the datasheet I saw that the minimum transition time is 7μs but the rate of the loop is 10μs.
Is that value only for one channel?

Solution

You obtain this behavior because you are using more than one I/O node. If you want to reach a 7μs rate you must use just one I/O node for more channels as showed in the following picture.
 

Additional Information

  • If you generate at difference frequencies you can use some local variables to use just one I/O node for output

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