Frequency measurement error using DAQSTC

[Jvi]

I have modfied the example listed to measure up to 9 frequencies continuosly in the vi as attached.
When I use the same approach combined with analogue & digital input/output I get a small error in frequency.
(Input line PF10 reads 6.8Hz for a 6.7Hz input.)

[Bill B]

Hello,

The code that you are using to take the frequency measurement could be done with lower level VIs that will more than likely resolve this issue. I modified one of the LabVIEW shipping examples: Measure Period (DAQ STC).vi Please take a look at the VI that I have attached.

[Jvi]

Hi,
This is similar to my original version.
I changed it because after checking all the signal conditioning I had the same problem and ran out of ideas (count reading too high and variable). On initial tests the new version was OK but it is not consistent and much slower to update.
When using only Counter, Analogue Inputs and Digital IO it seems better than when using all plus Analogue Output as well.
I have seen items relating to synchronising pads is this an issue?
Thanks