Experimental Physics and
Industrial Control System

"Peregrine M. McGehee" <[email protected]> · Thu, 12 Mar 1998 11:14:46 -0000

Jeff, 
> 
> It sounds like your immediate problem is that you need to guarantee 
> that a certain set of request have completed before initiating another 
> set of requests. It appears that ca_put_callback() will provide proper
> synchronization without resorting to ugly and complex code in your 
> client side application.

However, sole reliance on ca_put_callback as a command completion mechanism
may present problems for database designers in regards to lock-set
management since the records dealing with command completion may be linked
with the underlying mechanism database. 

Although multiple record solutions create their own difficulties due to
avoiding behavior such as "false NOT-BUSYs" there are ways to mitigate
this. Techniques used in the CAD/CAR model include tracking the CAD record
Client ID field and designing  subsystems so that they transition to the
IDLE state before BUSY when processing new commands.  

Aloha,
	Peregrine

Peregrine M. McGehee			Project Engineer: LEDA Control System
(505) 667-3273				[email protected]	
LANSCE-8 Controls & Automation	Los Alamos National Laboratory

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System