RE: [EXTERNAL] Representing stateless device commands?

["Feister, Scott via Tech-talk" <tech-talk at aps.anl.gov>]

Thanks Steven and Mark, for your welcoming and helpful responses.

 

I have the streamDevice proto files written, and am at the point where I’m wondering if there’s an easy way to capture what Steven is suggesting – forcing the PV back to zero immediately after the RS232 command “IncreaseBrightness” has been sent, such that the state of the binary PV “MYLED:IncreaseBrightness” represents whether we are “in process” of “Increasing Brightness”?

 

Here’s what I have in mind as far as sequence:

 

1. “MYLED:IncreaseBrightness” is 0, its regular state.
2. I invoke “caput MYLED:IncreaseBrightness 1”, changing the PV from 0 to 1.
3. StreamDevice follows its protocol for processing a change in the PV, and sends an RS232 message of “IncreaseBrightness” to the device. StreamDevice awaits no reply, as the device gives none.
4. [Somehow?] “MYLED:IncreaseBrightness” is now automatically forced back to 0.

 

I have steps 1-3 under control with StreamDevice, so I’m wondering about best practices to implement Step 4.

Thanks!

 

Scott

 

 

From: Hartman, Steven <hartmansm at ornl.gov>
Sent: Friday, January 5, 2024 1:22 PM
To: Feister, Scott <scott.feister at csuci.edu>
Cc: tech-talk at aps.anl.gov
Subject: Re: [EXTERNAL] Representing stateless device commands?

 

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On Jan 5, 2024, at 1:47 PM, Feister, Scott via Tech-talk <tech-talk at aps.anl.gov> wrote:

My approach right now is to call them binary outputs (bo) records

 

 

 

Welcome to the forum.

 

Yes, that sounds about right. 

 

You can use the ONAM and ZNAM fields of the BO record to name the two states which may convey that it is indeed a process variable that is either doing something (i.e., increase the brightness) or not. In EPICS, pretty much everything is a process variable. 

 

-- 

Steven Hartman

hartmansm at ornl.gov