Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Mon, 10 Aug 2015 16:36:37 -0500

Hi Mike,

On 08/10/2015 03:40 PM, [email protected] wrote:
> I have a question. The limit for a periodic record like calc example is
> 10 seconds. I want to create a periodic record to change a value every
> hour. Is there a possibility? And how can I use a GUI to set parameters
> like voltage?

The set of scan periods that can be used is determined by the IOC at
startup from the set of choices defined in its menuScan menu — it scans
the numbers given in the choice strings. You can add new scan periods by
copying the menuScan.dbd file from your copy of EPICS Base into the
source directory where you build your IOC (don't rename the file), then
edit the file and add new choices to the menu definition keeping the
order the same (slow to fast). When you next rebuild the IOC it should
then read the new menuScan.dbd file instead of using the one from Base
and allow you to use the new scan periods.

If you're using 3.15 you can even specify the scan period in minutes,
hours or Hertz, but 3.14 only understands seconds. These are all valid
choices in 3.15:
    choice(menuScan1_hour,      "1 hour")
    choice(menuScan0_5_hours, "0.5 hours")
    choice(menuScan15_minutes, "15 minutes")
    choice(menuScan5_minutes,   "5 minutes")
    choice(menuScan1_minute,    "1 minute")
    choice(menuScan10_seconds, "10 seconds")
    choice(menuScan5_seconds,   "5 seconds")
    choice(menuScan2_seconds,   "2 seconds")
    choice(menuScan1_second,    "1 second")
    choice(menuScan2_Hertz,     "2 Hertz")
    choice(menuScan5_Hertz,     "5 Hertz")
    choice(menuScan10_Hertz,   "10 Hz")

For 3.14 IOCs you would have to use
    choice(menuScan3600_seconds, "3600 seconds")
to get a 1-hour periodic thread.

There are various alternative ways to do what you want, a calcout record
decrementing a counter would probably be the simplest example.

HTH,

- Andrew

-- 
Light thinks it travels faster than anything but it is wrong.
No matter how fast light travels, it finds the darkness has
always got there first, and is waiting for it.
    -- Terry Pratchett, Reaper Man

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System