Re: Recommendations for EPICS Based Data Acquisition System

[Matt Rippa <mrippa@gemini.edu>]

Hi Mark,

Is your MC EPICS driver support for Windows only? If all the drivers were

EPICS-OSI compatible, that would put MC on our short list.

Based on your recommendation a couple years ago, we use the MC

devices in our new vibration monitoring system. That uses linux drivers,

but there's no EPICS support (yet). It works very well for our needs.

I'm coming to the conclusion that FPGA's make little or no sense in this

system ( which has relatively pedestrian control requirements) . 

-Matt

On Thu, Dec 7, 2017 at 5:32 PM, Mark Rivers <rivers@cars.uchicago.edu> wrote:

Hi Matt,

It's possible that there are low-cost USB solutions that would meet the specs.

Analog input
https://www.mccdaq.com/usb-data-acquisition/USB-1608G-Series.aspx

Analog output
https://www.mccdaq.com/usb-data-acquisition/USB-3100-Series.aspx

Digital I/O
https://www.mccdaq.com/usb-data-acquisition/USB-DIO32HS-Series

I have good experience with products from this company.  I have an EPICS drivers for the analog input models above.
<http://cars9.uchicago.edu/software/epics/measCompMultiFunctionDoc.html>
http://cars.uchicago.edu/software/epics/measCompMultiFunctionDoc.html

All of these models also have digital I/O and some have a few analog outputs as well.

I seems like the processing required might be done in a multi-core modern CPU?

Much cheaper than VME or the development costs of FPGA.

Mark





________________________________
From: Matt Rippa <mrippa@gemini.edu>
Sent: Thursday, December 7, 2017 4:29 PM
To: Mark Rivers
Cc: Talk EPICS Tech; Rolando Rogers
Subject: Re: Recommendations for EPICS Based Data Acquisition System

Hi all,

Thanks for the replies.

Here's more info:


Can you describe a bit more the specifications and how it operates?

- How many inputs at 5 kHz?

Attached is a cut sheet. There's 38 analog and 14 TTL inputs.


- How much calculation to determine the outputs?

We have two core processing tasks for mirror position and vibration control.
This results in a total of 5, 3x3 matrix vector multiplies per cycle. This is to
transform for linear sensor space to AZ/EL tip tilt coordinates.

The legacy DSP's are TI-TMS320.


- How many outputs to be written, and at what rate?

All the stepper motor control is implemented with TTL lines. So a 20 Hz stepper clock
is realized by skipping sufficient 200 us cycles to generate the clock.
Again, the IO cut sheet shows this as 35 outputs. But only the motors are using the sample rate.


- Is this just for feedback control, or do you need to log the inputs and if so at what rate?

I'm keen on logging inputs up to the sample rate in an engineering mode if it's easy to do.
This would be very useful for tuning the system. At a minimum I'd want to log the inputs at
1 kHz. The closed loop bandwidth of the system is about 100 Hz.

I have a wealth of information if you're interested to understand this better.


-Matt




Mark



________________________________
From: tech-talk-bounces@aps.anl.gov<mailto:tech-talk-bounces@aps.anl.gov> <tech-talk-bounces@aps.anl.gov<mailto:tech-talk-bounces@aps.anl.gov>> on behalf of Matt Rippa <mrippa@gemini.edu<mailto:mrippa@gemini.edu>>

Sent: Wednesday, December 6, 2017 2:54 PM
To: Talk EPICS Tech
Cc: Rolando Rogers
Subject: Recommendations for EPICS Based Data Acquisition System

Aloha,

I'm looking for your recommendations on the latest data acquisition
hardware, compatible with EPICS.

Our Secondary Mirror system at Gemini has a 1 meter diameter,
55 kg mass. There's 3 degrees of freedom and a 5 kHz control loop.
The system was designed in the 90's by Lockheed Martin, based on
a DOS PC with an ISA backplane (PICMG 1.0) and a DSP data
acquisition board with 16 bit ADC's and DAC's. The DOS PC interfaces
with an EPICS IOC via Reflected Memory.

In 2010 I did a conceptual redesign based on a Hytec Blade 9010 using
IP cards and an Intel CPU running RTEMS. Today it seems FPGA's are
a popular choice for data acquisition. Perhaps a Xylinx zynq solution?
Would anyone still consider VME?

I have no requirement for 5 kHz EPICS control.  Although that's intriguing.

Thanks for your time.

-Matt