[dsg-svt] [New Logentry] SVT MFCs stopped flowing, reboot of gas system's SF cRIO fixed error.

[tlemon at jlab.org]

Logentry Text:
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Yuri called requesting DSG look into zero flow for SVT nitrogen system.

When connecting to each of the four SVT MCFs individually through the MKS example VI, we saw that flows did not match the EPICS set points. We could set the flow for each flow meter using the VI, but it the flow reading was not shown in EPICS and reverted to zero when the VI was stopped.

Looking at the expert tab on the main gas system GUI (available on screen in gas shed), we could see that the reinitialization count for the space frame MFCs had increased. The LabVIEW program has a condition that if the MFCs are unsuccessfully initialized three times, it stops all MFC subVIs.

We rebooted the SF cRIO and the flow to SVT returned to normal when the cRIO came back online.

Talking to Yuri after the flow was restored, he mentioned Hall B Engineering moved the MFCs earlier this morning. Most likely, the MFCs were disconnected from network, causing the LabVIEW program to try to reinitialize the MFCs. When the program could not do so, it stopped the MFC VIs. When the MFCs were reconnected to network, the cRIO would have need to be restarted to be able to flow nitrogen again.

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