At 08:51 AM 10/12/2006 -0500, you wrote:
i did see that there were a great many hits on google before posting and have
been sifting through what's already available for a few hours now. i wanted to
see if anyone could suggest something in particular as being "better". the
qualifier of "any" was a poor choice on my part.
In general, any programming language can be used for PLC work; there are
two main questions:
1) What I/O HW is invovled?
and
2) How do you communicate with it.
i am none too keen on using linux for such a task and would prefer to
remain an
openbsd purist if at all possible. are there any ports or packages for
this sort
of stuff?
Many of the OS projects are oriented towards 'Real Time' processing and
'Ladder Logic'. RT aspects, if critical cannot be ignored; I have never
seen a project that actually REQUIRED RT processing however. The majority
of I/O requirements are FAR slower than any latency in the OS (except for
Windoze, of course).
As far as Ladder Logic, you don't really need it. We have done a number of
projects with various languages, .. in most cases, running a 'Node
Controller' (embedded client PC) using a variety of OS. H/W was either
direct attached (memory/I/O communications), USB, or Ethernet.
You can even use 'standard' PLCs for the H/W, communicating with them via
Ethernet or even WiFi. Most PLC manufactures have interfaces you can use
for external control.
HTH,
Lee
