Experimental Physics and
Industrial Control System

Heinrich du Toit <[email protected]> · Wed, 22 Aug 2007 07:48:46 +0200

Hi

Ok what you say makes sense but not completely.
As the interrupt callback is already called from inside the ASYN thread
(true?)
then the interrupt callback wouldn't need to go throught queueRequest
todo anything and can therefore use the ASYN interface functions
directly?

The reason I'm asking this is for the case of a custom record:
Say the record is connected to ASYN ports A,B and C. Which could be
different interfaces or maybe just other settings.
Anyways.
If callback A is called... then it should be ok if the record reads
directly into B and/or C. Because it is already in the ASYN thread and
therefore there shouldn't be any problems or need for queueRequests and
so forth.

Or should the record rather install 3 different interrupts?
Wouldn't that in the end result in a lot of exstra db updates?

I guess my next question will be about what happens when a record starts
sending db_update floods :)

-Heinrich

On Tue, 2007-08-21 at 09:09 -0500, Mark Rivers wrote:
> Hi Heinrich,
>  
> You should use the data value that is passed in the callback. 

>  The interrupt callback should never call the read function in the asyn interface directly (it would need 

> to go through queueRequest to ensure that the read runs in the port thread in case the driver is asynchronous, 

> and to ensure correct locking even for synchronous drivers).  In principle it could call queueRequest, and then 

> call read() from the queueRequest callback, but there's really no need to do that.
>  
> Mark
>  
> 
> ________________________________
> 
> From: [email protected] on behalf of Heinrich du Toit
> Sent: Tue 8/21/2007 8:44 AM
> To: Tech-Talk EPICS
> Subject: asyn - interrupts
> 
> 
> 
> Hi
> 
> Just want to make sure about something and what is the general practice
> that should be used.
> 
> When an interrupt callback is called.
> Then there is an parameter to send the "new" data in also.
> 
> Ok so when the record support code's interrupt callback is called it
> already receive the new data...
> But it can obviously still call the read command for the asyn interface
> and get the data that way.
> 
> So do we assume that the data passed to the interrupt callback is
> correct and that no further asyn calls is needed. Or can/should it still
> call the read function to get data?
> 
> I'm assuming it accepts the data in the callback and go ahead with that
> as that would make sense to me.
> 
> -Heinrich
> 
> 
> 

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System