Upgrading the Fermilab Linac local control system Page: 2 of 3
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tings) would be equipped with a Rack Monitor (RM). The rack
monitor, as built for D0, contains eight twelve-bit D/A channels,
64 (unheld) twelve-bit A/D channels, four 16-bit words of digital
I/O and aMIL-STD-1553B interface. A 32-channel sample-and-
hold chassis would be needed to use the digitizer on the RM. The
rack monitor gets its name from the fact that the interface to all
the equipment in a 19-inch rack can usually be made through one
The second method. Figure 3b, uses a new Motorola chip
designed to control a modem automobile engine, the MC68332
microcontroller. This 68020-based chip includes sixteen
counter/timer channels, a serial communications interface, two
kbytes of RAM and a system integration module. This processor
is available as a small subsystem called a Business Card Com-
puter (BCC), a 2.2S by 3.5 inch circuit board that has the
MC68332, 128 kbytes of PROM, 64 kbytes of RAM and an RS-
232 serial interface.
We would incorporate this BCC into a new type of rack
monitor creating a Smart Rack Monitor (SRM, ). The BCC
would attach to the motherboard of the SRM through its two
64-pin DIN connectors. All the address, data, control and I/O
pins of the MC68332 are available on these two connectors. In-
cluded on die silicon of the chip is an extensive system integra-
tion module—a collection of interface features normally provid-
ed by peripheral chips. A SRM would add the following func-
tions: Tevatron-style clock decoder, ARCnet local-area network
interface to the VME master, eight bytes of digital I/O, sixteen-
channel D/A, twelve-bit S&H A/D and a 64-channel analog
multiplexor. We have designed new nine-byte digital I/O daugh-
ter cards to communicate with the old linac equipment. Two
would be needed for each SRM.
The control system alternative with SRM's would be less
expensive, more powerful and faster than the other alternative.
Unfortunately, we do not yet have a clear idea of how to write the
software to drive the SRM.
The decision as to which type of interface to use is imminent.
When the decision is made, we will order the hardware necessary
to convert completely the old linac control system to the system
described above. We will assemble the new stations at their final
locations, load the appropriate local data base and perform thor-
ough testing off-line before the actual changeover. We anticipate
it will take less than a week to perform the switch, but, naturally.
Mmr Unac Confrcf Steftart Dcmmln
Figure 4, The controls system for the Upgraded Linac
we expect a somewhat longer unstable period. We hope to have
the new system for the old linac installed by the summer of 1991.
This new system will remain in place, controlling the old linac,
for about a year. The last four tanks of the old linac, along with
that part of the control system, will be removed as the new linac
is rolled in.
Control System for the New Linac
The new linac addition at Fermilab is detailed elsewhere at
this conference . The major aspects of that system are as
follows. The H- beam exiting tank five, at 116 MeV, is captured
by an 805 MHz transition section and injected into a seven-
module side-coupled-cavity accelerating structure. The 805 MHz
modules fit in the space vacated by our old tanks six through nine
which now accelerate the beam to 204 MeV. The beam in the
new structure is accelerated to a final energy of 401 MeV. This
higher-energy beam is easier for the next accelerator, the Booster,
to handle because of a 75% reduction in the space-charge tune
shift there. The two small transition section cavities, the seven
large accelerating modules and the debuncher cavity are powered
by 805 MHz klystrons. The seven accelerating modules each use
a 12 MW klystron under development by Litton: the other three
smaller cavities are driven by a pulsed-version of a UHF-TV
channel 69 80-kW-cw klystron.
The following control system is being built for the 805-MHz
part of the new linac, see Figures 4 and 5. The control stations are
connected to each other and to the rest of the world by token ring.
The system interfaces with hardware subsystems either through a
VI to a slave VME subsystem or through rack monitors (smart or
dumb). Each control station manages two major systems, usually
two klystron RF systems. A color console is located at each con-
trol station to give local access to the information.
There are several distinct subsystems in each RF station.
Modulator and low-level RF computer-controlled subsystems are
being developed. Conventional water systems, beam diagnostics
and safety systems are also being built. How each of these inter-
faces to the control system is described here .
The modulator and low-level RF subsystems both contain a
smart controller in, respectively, VME and VXI environments.
Communications occur through VME memory over a VI. Each
smart subsystem will perform its own A/D and D/A conversions.
The local intelligence of these systems will provide the pertinent
digitized readouts in a contiguous block of VME memory which
the master control station can read, over the Vis, at 15 Hz. A
similar block of contiguous memory will be provided by each
8Q2.5 Token Ring
Figure 5, Detail of a single control station for the new Linac.
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McCrory, E.S.; Goodwin, R.W. & Shea, M.F. Upgrading the Fermilab Linac local control system, article, February 1, 1991; Batavia, Illinois. (digital.library.unt.edu/ark:/67531/metadc1100591/m1/2/: accessed November 19, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.