[Halld-controls] FCAL-II controls discussions

Thu Mar 23 14:55:37 EDT 2023

Beni, that assumes that the ADC effectively uses 16 bits and is also set to 0-5V range.

The step size seen in the archiver data is 0.022kPa, which is very close to 1mV change from the sensor.  The document https://literature.rockwellautomation.com/idc/groups/literature/documents/um/1769-um002_-en-p.pdf shows that the ADC can use 15 bits for 0-10V, or can use the same 15 bits for 0-5V mode. Table 3.8 in the same document shows the effective resolution of the ADC channels for different filter frequency, and my understanding of that table is that at the 50/60Hz filter frequency  setting the effective resolution of the ADC channel is 1mV (called 1mV/count in the table). Since Bobby or Nick configured the ADC with the filter frequency to 60Hz, that is apparently what we are seeing.

I would try running that ADC with 10Hz frequency filter instead of 60Hz, but only for the newly bought sensor, and see if we get a better resolution in MYA. Of course, now we are talking about measuring a fraction of millivolt increments which probably means that it will not be a very accurate measurement, but that is a different issue.

But in general, this sensor, according to its specs, has uncertainty of 1.5kPa over the full dynamic range which is 10 times larger than the alarm limit we are setting.

Hovanes.

________________________________
From: Halld-controls <halld-controls-bounces at jlab.org> on behalf of Beni Zihlmann via Halld-controls <halld-controls at jlab.org>
Sent: Thursday, March 23, 2023 11:55 AM
To: halld-controls at jlab.org <halld-controls at jlab.org>
Subject: Re: [Halld-controls] FCAL-II controls discussions

According to the spec sheet the sensitivity of the sensor is 21.8 Pa/mV  (0 to 5V range)
the sensitivity of the ADC is 0.076mV/ADCcount
So the digitizer is way more sensitive than the sensor.

cheers,
Beni

On 3/23/23 11:22, Bobby Bunton via Halld-controls wrote:
Hello all,

Per our discussion in the controls meeting today, here is the information that was requested.
This is the pressure sensor we are using, Apogee instruments SB-100 barometric pressure sensor
https://www.apogeeinstruments.com/sb-100-barometric-pressure-sensor/?gclid=Cj0KCQjw8e-gBhD0ARIsAJiDsaXMs3PuHfNMhwpBGExj1jN6KtLCpGJEFnUSc3kbAtm8uM88eItx8jIaAsGDEALw_wcB#product-tab-description

And the PLC module that is reading it is a compact i/o 1769-IF8, the module is configured with the 60hz selection filter

https://literature.rockwellautomation.com/idc/groups/literature/documents/in/1769-in067_-en-p.pdf

Also ive already switched the old sensor back to being the input for barpress1 and put an offset on the barpress2 channel so that they more closely agree, please let me know if there is any more information you need.

Thanks,
Bobby
[https://cdn11.bigcommerce.com/s-0oei9zu/products/81/images/2992/baro-top-down__22994.1586801524.220.220.jpg?c=2]<https://www.apogeeinstruments.com/sb-100-barometric-pressure-sensor/?gclid=Cj0KCQjw8e-gBhD0ARIsAJiDsaXMs3PuHfNMhwpBGExj1jN6KtLCpGJEFnUSc3kbAtm8uM88eItx8jIaAsGDEALw_wcB#product-tab-description>
SB-100: Barometric Pressure Sensor<https://www.apogeeinstruments.com/sb-100-barometric-pressure-sensor/?gclid=Cj0KCQjw8e-gBhD0ARIsAJiDsaXMs3PuHfNMhwpBGExj1jN6KtLCpGJEFnUSc3kbAtm8uM88eItx8jIaAsGDEALw_wcB#product-tab-description>
The SB-100 provides an accurate, stable, and durable measurement of barometric pressure at an affordable cost.
www.apogeeinstruments.com<http://www.apogeeinstruments.com>

________________________________
From: Halld-controls <halld-controls-bounces at jlab.org><mailto:halld-controls-bounces at jlab.org> on behalf of Hovanes Egiyan via Halld-controls <halld-controls at jlab.org><mailto:halld-controls at jlab.org>
Sent: Friday, March 10, 2023 9:17 AM
To: halld-controls at jlab.org<mailto:halld-controls at jlab.org> <halld-controls at jlab.org><mailto:halld-controls at jlab.org>
Subject: [Halld-controls] FCAL-II controls discussions

Hi all,

I scheduled an extra meeting for next Thursdays, March 16, at 10am to discuss slow controls for FCAL-2 in details. Sasha will be presenting the requirements. There will be no other topics on the agenda for that meeting.

We will have our regular Hall D controls meetings based on the usual schedule.

Hovanes.

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