daniel.sigg@LIGO.ORG - posted 13:09, Wednesday 29 January 2014 - last comment - 18:16, Wednesday 29 January 2014(9629)
DAQ/dataviewer limitation?
We are trying to record the frequency of the ifr, but there is a 4Hz offset between the EPICS readback and the value reported by dataviewer and/or saved by the DAQ.
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Looks like a dataviewer/xmgr problem. When plotting this data using diaggui we get the correct value.
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the eagle eyed amongst you will have noticed the root plot Y-axis doesn't look correct. The data line is 2256 but the Y-range is actually 2260 to 2270 suggesting the data is 2260 (as xmgr showed it). Jim ran command line nds client on this channel and confirmed the DAQ is recording the correct frequency of 24992256Hz. Unfortunately both xmgr and root seem to have plotting problems with static numbers of this magnitude.