Experimental Physics and Industrial Control System
A problem which caused some communication errors between the APS EPICS
control system and devices controlled by BITBUS, including the Storage
Ring power supplies, has been solved and repaired. By designing and
building a hardware BITBUS analyzer, Ned Arnold identified three
different types of problems and established that they were all caused
by the PEP VME BITBUS interface board. The two most troublesome
problems (those which caused the communications to hang) were fixed
two months ago by modifying the EPICS drivers to work around the PEP
problems. The third type of error, which was not fatal but would cause
nuisance alarms, has now been repaired. This repair required obtaining
the source code for the VME module from PEP and then debugging this
code. The Code was obtained via a non-disclosure agreement with PEP.
The code was written in PLM with German comments (Marion White, an APS
Physicist, translated). The problem area in the code was identified,
and the prom was then hand patched. All PEP boards in the PAR,
Booster and Storage Ring have been upgraded approx. 25 boards * 2
links/board = 50 links. No errors attributable to the PEP VME BITBUS
interface board have occurred since the repair was completed.
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