Experimental Physics and
Industrial Control System

> From [email protected] Tue Nov 22 08:35 CST 1994
> Date: Tue, 22 Nov 1994 07:33:51 -0700
> From: [email protected]
> To: [email protected]
> Subject: Lock sets for read access
> X-Sun-Charset: US-ASCII
> Content-Type> : > text> 
> Content-Length: 558
> 
> 
> I'd like to transmit a number of parameters from a major component of our control
> system down to one of its subsystems with the requirement that all of the
> parameters are consistent. In order to do this it seems that I have to be
> able to disallow read access of the process variables when they are being 
> updated.
> 
> So, my thoughts are:
> 1) Do lock sets inhibit read access as well as write and process access?

Starting with 3.12 reads from outside the database, i.e. from channel access,
lock. Previously this was not true. Note however that each individual read
locks. Thus if you have a series of ca_gets you will not get what you want.

> 2) If not, I suspect I'll have to set up a semaphore - perhaps using 
> PERMISSIVE records?
> 
> 3) How is this 'traditionally' done?
> 

No tradition.

Marty Kraimer

Navigate by Date:

Prev: Lock sets for read access mcgehee

Next: Release Numbers Steve Lewis

Index: <1994>  1995  1996  1997  1998  1999  2000  2001  2002  2003  2004  2005  2006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  2019  2020  2021  2022  2023  2024 

Navigate by Thread:

Prev: Lock sets for read access mcgehee

Next: Re: Lock sets for read access Tim Mooney

Index: <1994>  1995  1996  1997  1998  1999  2000  2001  2002  2003  2004  2005  2006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  2019  2020  2021  2022  2023  2024