Re: Newport ESP300 on Linux

[Tim Mooney <mooney@aps.anl.gov>]

Patrick Thomas wrote:
> Hi,
>
> I'm trying to control a rotation stage connected to a Newport Universal 
> Motion Controller / Driver, Model ESP300, connected to a Linux box by a 
> Comtrol DeviceMaster RTS. Is there device support available for this? I 
> have inherited a database and SNL code which runs on a VME box. I 
> believe it uses C calls to open a device file and control the ESP300. I 
> am now trying to move it over to a Linux box, but I'm new to EPICS. I've 
> gone through some of the documentation, and watched some of the 
> introductory talks, but I'm still not quite sure how to do this. My 
> impression is, someone changes a process variable in the MDM screen, and 
> this triggers an appropriate record to be processed. I'm not sure how 
> the SNL comes in however, or what happens when a record is processed. 
> Any help would be very welcome.
> Thank you for your time.
An SNL program gets into the act by monitoring the value of an EPICS PV.
When the value of a PV it's monitoring changes, the SNL program will receive
an event.  It's not essential that a record process for this to happen;
anything that causes a PV's value to be posted can trigger action by an
SNL program.

Most PV's are posted as a side effect of the CA call that caused them to
change.  The exception is the VAL field, which is only posted when the
record that owns it specifically asks for it to be posted.

--
Tim Mooney (mooney@aps.anl.gov) (630)252-5417
Beamline Controls & Data Acquisition Group
Advanced Photon Source, Argonne National Lab.