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Entry  Fri Dec 8 23:31:31 2017, johannes, Frogs, ASS, c1ass slow channel offloading scripts with small  
    Reply  Wed Dec 13 09:49:23 2017, johannes, Update, ASS, wiring diagram 1Y9.pdf
       Reply  Thu Dec 14 00:32:56 2017, johannes, Update, ASS, Acromag new crate; c1auxex2 configured as gateway server for acromag fp_mod_4U.pdfIMG_20171213_171541850_HDR.jpg
          Reply  Thu Dec 14 23:27:46 2017, johannes, Update, DAQ, aux chassis design auxdaq_40m_4U_front.pdfauxdaq_40m_4U_rear.pdfauxdaq_40m_4U_DSub37x2.pdfauxdaq_40m_4U_IDC50.pdf
             Reply  Tue Jan 9 00:07:03 2018, johannes, Update, DAQ, etmx slow daq chassis 
                Reply  Wed Jan 10 22:24:28 2018, johannes, Update, DAQ, etmx slow daq chassis 
                   Reply  Thu Jan 11 09:57:17 2018, Steve, Update, DAQ, acromag at ETMX Acromg_in_action.png
                   Reply  Thu Jan 11 20:59:41 2018, gautam, Update, DAQ, etmx slow daq chassis 
                      Reply  Wed Jan 17 14:32:51 2018, gautam, Update, DAQ, Acromag checks OSEMPDmon_Acro.png
                         Reply  Wed Jan 17 22:44:14 2018, johannes, Update, DAQ, Acromag checks 
                            Reply  Sun Jan 21 13:11:25 2018, johannes, Update, DAQ, Acromag checks 
                   Reply  Fri Jan 12 10:02:05 2018, johannes, Update, DAQ, etmx slow daq chassis 
                      Reply  Fri Jan 12 19:15:34 2018, johannes, Update, DAQ, etmx slow daq chassis 
                         Reply  Wed Jan 24 18:12:31 2018, johannes, Update, DAQ, ETMX auxiliary DAQ work IMG_20180124_120202019.jpgIMG_20180124_120123064.jpgIMG_20180124_120219278.jpgIMG_20180124_120059765.jpg
                            Reply  Wed Jan 24 19:17:06 2018, johannes, Update, DAQ, c1auxex2 startup behavior 
                               Reply  Wed Jan 24 23:13:30 2018, johannes, Update, DAQ, c1auxex2 startup behavior 
    Reply  Thu Dec 14 19:33:20 2017, gautam, Frogs, ASS, c1ass slow channel offloading scripts with small  
Message ID: 13554     Entry time: Wed Jan 17 22:44:14 2018     In reply to: 13553     Reply to this: 13565
Author: johannes 
Type: Update 
Category: DAQ 
Subject: Acromag checks 

This happened because there are multiple ways to scale the raw value of an EPICS channel to the desired output range. In the CryoLab I was using one way, but the EPICS records I copied from c1auxex were doing it differently. Basically this:

DTYP  - Data type -
LINR "NO CONVERSION" vs "LINEAR"
RVAL Raw value
EGUF Engineering units full scale
EGUL Engineering units low
ASLO Manual scaling factor
AOFF Manual offset
VAL Value

If the "LINR" field is set to "LINEAR", the fields EGUF and EGUL are used to convert the raw value to the channel value VAL. To use them, one needs to enter the voltages that return the maximum and minimum values expected for the given data type. It used to be +10V and -10V, respectively, and was copied that way but that doesn't work with the data type required for the Acromag units. For -some- reason, while the the ADC range is -10V to +10V, this corresponds to values -20000 to +20000, while for the DAC channels it's -30000 to +30000. I had observed this before when setting up the DAQ in the CryoLab, but there we were using "NO CONVERSION", which skips the EGUF and EGUL fields, and used the ASLO and AOFF for manual scaling to get it right. When I mixed the records from there with the old ones from c1auxex this got lost in translation. Gautam and I confirmed by eye that this indeed explains the different levels well. This means that the VMon channelsfor the coils are also showing the wrong voltages, which will be corrected, but the readback still definitely works and confirms that the enable switches do their job.

Quote:
  1. I take back what I said about the OSEM PD mon at the meeting - there does seem to be to be some overall calibration factor (Attachment #1) that has scaled the OSEM PD readback channels, by a factor of (20000/2^15), which Johannes informs me is some strange feature of the ADC, which he will explain in a subsequent post.

 

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