Experimental Physics and Industrial Control System
Subject: |
Re: Lock sets for read access |
From: |
[email protected] (Marty Kraimer) |
Date: |
Tue, 22 Nov 1994 08:49:25 -0600 |
> 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
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