I should have mentioned that the abDf1 driver functions
virtually flawlessly.
However, there is a suspected bug in one of our vxWorks drivers:
either the AbDf1 or CmSx (a driver for the older Compmotor controllers -AX?- which
was also written for the Keck observatory by Jeff Hill but with major additions
by me). I have spend a lot of time trying to find that bug to no avail. The
problem could be in the CmSx driver and not the AbDf1 driver, but, the outgoing
task, when the page 0 write, occurs is typically AbDf1. As the problem may not
occur for years (seemingly until the electrical slip rings become noisy –i.e.
the serial connection to the AB PLCs) it is hard to find and rarely affects
operations.
Al
At the Keck observatory we are still driving our dome
enclosures with two Allen Bradley SLC 5 PLCs (one is the 500 and the other is
older) using the abDf1 driver (that is a one not an eye J), which was written for the
observatory by Jeff Hill in 1995 (there have been a few tweaks in the
intervening years – some by Nick Rees, I believe- but they are minor).
The abDf1 driver requires drvSerial, which was also written for the observatory
by Jeff Hill in 1995 (we have tweaked that driver as well).
Both drivers have been further modified so that they can
function in a Unix IOC (R 3.14.n), separate drivers I think. We control other
Allen Bradley PLCs (including, I think, a couple of RSLogix PLCs that are used
for laser safety systems – I can confirm that if you need) from Unix
IOCs.
If you have the AB manuals, for the older PLCs, the
DF1 protocol is described in detail therein.
Allan Honey
We have a number of old Allen Bradley PLC implementations
here at SLAC. One of these uses a Data Communication Card (DCM) in VME is
connected to the SLC5 SLC500s. One path we are considering is using an RSLogix
PLC (which has good EPICS support) as the master PLC, and slaving the SLC5 PLC
to that. It turns out that there exists a package to translate the ladder logic
from SLC500 to RSLogix.
Another group here is asking the following:
“We have some old SLC 5/04 PLCs from Allen Bradley
that we wanted to make EPICS compatible. I found a third party SLC module that
talks Ether/IP:
Will this module work to provide the EPICS support?
“
Another piece of information is from Ernest Williams: He
warned us against the direct SLC-50x EPICS driver support, since it uses its
own protocol (DFI?) and has a poor reputation and poor support.
So the questions to the community are
How are you reviving old PLC support? What has or has not
worked? What do you recommend?