Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Tue, 17 Mar 2009 10:01:52 -0500

Hi Maren,

On Monday 16 March 2009 20:23:51 Maren Purves wrote:
> Can you have several records talk to the same piece of hardware without
> manually disconnecting? (I'm sure it depends on the hardware, but I can
> think of a few where that wouldn't work - and even if you disconnect
> manually, how do you control which record connects the next time?).

Many device support layers work Ok with multiple records pointing to the same 
hardware address, although obviously some may have been written without that 
in mind and could break if you do that.  I guess the main source of problems 
could be asynchronous devices, but in many cases the underlying driver 
support is able to handle multiple record types anyway and this generally 
requires authors to put the necessary locking and queuing infrastructure into 
the support anyway.

Of course having multiple output records driving the same signal could be a 
recipe for user confusion if the device doesn't have readback and value 
update functionality, so this isn't really recommended.

- Andrew
-- 
The best FOSS code is written to be read by other humans -- Harold Welte

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System