Experimental Physics and
Industrial Control System

Peter Milne <[email protected]> · Tue, 08 Nov 2005 08:57:41 +0000

Hi All
I've recently ported BASE 3.14.7 to run on linux-xscale (so that our
intelligent digitizers now have IOC functionality on board).

The patch to build the IOC is available here:
http://www.d-tacq.com/epics.shtml
The port was very straightforward, thanks to the excellent EPICS build
system. If anyone is planning to repeat this exercise, the only issue
with xscale (and probably any little-endian ARM processor) on Linux is
that the floating point library has another take on little-endianness
compared to the norm - easily corrected as shown in the patch.
A second point that may be of interest to list members is Device Support
for Sysfs:
It's increasingly common in modern Linux systems to use device files on
Sysfs to enable simple user space access to kernel parameters. Or in our
case, to nail up a Linux VFS with a file per channel. I couldn't find
suitable Device Support for this functionality, so I wrote a simple but
generic "dsSysfs" device support interface, using "ai" records and
encoding the location and characteristics of the files in the INP field.
So, for example, it's easy to create records for
AI monitoring:

field(INP, "@/dev/mean/01 rb4") # reads the rolling mean for channel
01 as a 4 byte integer

...

field(INP, "@/dev/mean/96 rb4") # reads the rolling mean for channel
96 as a 4 byte integer
Heartbeat (generic to any Linux system) :
field(INP, "@/proc/uptime")            # read the ascii data from this file
or even
System health monitor:

field(INP, "@#!sysmon -T 1") # read the [ascii] result of
spawned task sysmon (temperature monitor).
The source code and doc is freely available at
http://www.d-tacq.com/epics.shtml
If there already is the means to do this in EPICS, do let me know, it
will be useful to compare features.
Thanks
Peter.
--
Peter Milne			[email protected]
D-TACQ Solutions Ltd		www.d-tacq.com

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System