Startup of the experimental physics industrial control system at NSTX Page: 2 of 3
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The server software runs on the input-output controller
(IOC), a VME crate with a single-board computer running
the vxWorks real-time operating system. The IOC's
contain the logic and sequencing for controlling the
process, and hardware modules for device-level I/O. The
client software runs on the "host" computer, a Sun
workstation running Solaris. Operators use an X-window
display and the client programs to command the process-
control software running in the IOC. An EPICS system
can have any number of IOC's, hosts, and X-terminals.
Using EPICS is easy. Getting EPICS to run can be
difficult for inexperienced users. Unlike most modern
commercial software packages you cannot merely pop in
a CD-ROM and hit the "Install" button. Software and
licenses must be purchased from several vendors. Several
EPICS, GNU Project, and other software utilities must be
downloaded from various sites on the internet. Once the
utilities are downloaded, they must be placed in proper
directories, environmental variables set, paths defined,
privileges granted, etc... and then compiled using the
unix Make utility.
Once the build-tools have been installed the building of
EPICS base can begin. This was not a trivial process
even though there were installation guides available.
However, implementing the simply-stated steps in the
guides took several weeks. The personnel developing the
EPICS at NSTX were hardware and process-control
oriented and not very experienced at unix administration.
Fortunately, others at the lab who had such experience
were available for consultation.
III. Wide Range of Skills
A wide range of skills are required to support an EPICS
system. This can present a challenge to small EPICS
development groups. The aforementioned unix system
administrator is needed first. Then programming skills
are typically used to configure and compile EPICS
extensions and to write or debug record, device, or driver
routines. Hardware engineering skills are required to
configure the IOC and I/O modules. Connecting a PLC
may require that the communication protocol and other
interfacing issues need to be understood in detail. And a
well-designed network is critical to achieve good system
A lack of practical experience in some of these areas can
lead to delays and frustration. If there is a problem a
small group may not have the expertise to quickly identify
and correct the cause. For example, the NSTX startup
effort lost several weeks due to faulty memory on the first
IOC computer that was installed. The bad hardware
was not discovered for several weeks, partly because of confidence
in the (new) Motorola hardware, and a commensurate lack of
confidence in the manner in which the (new) software was being
Table 1 summarizes the major skills needed to get the EPICS
base software to run. Each skill has a rating between one and
three. A three indicates that proficiency is essential for a fast
Table I. Skill/Proficiency for EPICS Building
Unix administration 3
C programming (C++ use growing) 3
vxWorks programming 2
network design 2
Make/GNUmake knowledge 2
Tornado/vxWorks administration 1
network administration 1
X-manager administration 1
firewall administration 1
VME and single-board computers 1
Fig. 2 below shows the relative sequence of when the various
skills were required. The operating system administration
effort must occur first, and eventually the process engineer
(user) becomes involved when defining the process-control
algorithms. Once the EPICS base has been established the
system administrator and software engineer assume a much
smaller support role.
* * S
Fig. 2 Diagram showing the sequence of skills necessary to
bring EPICS to a working state. Skills shown are operating
system administration, software engineering, hardware
engineering, and process-control engineering.
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Sichta, P. & Dong, J. Startup of the experimental physics industrial control system at NSTX, report, December 17, 1999; Princeton, New Jersey. (digital.library.unt.edu/ark:/67531/metadc702314/m1/2/: accessed August 18, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.