Control System of the IHEP Cryo Complex
A.Ageyev, V.Alferov, A.Dunaitsev, Y.Ivanov, A.Khvorostyanov, V.Krendelev,
A.Lukyantsev, V.Proshin, A.Sytin
Institute for High Energy Physics, Protvino, Russian Federation
The cryo complex was designed to supply the superconducting (SC) Magnet Test Facility (MTF) with liquid
helium and nitrogen. The control system is based on
IBM/PC's (MS-DOS) and the IHEP version of CAMAC
crates. Each crate houses an intelligent controller runninga home made operating system and application programs,
performing data acquisition and local control functions. Aspecial application program on the console PC's provides amultitask environment under MS-DOS. The programming
languages are C on PC and assembler on the crate controller. A hot reserve of electronics (50% of crates) as wellas an analog protection system provide a high reliability ofcontrols. Imitators of cryo equipment were designed forthe development of modules and applications.
The cryo complex is a part of the SC MTF for the UNK
project [1]. It consists of the central liquifier, 10 satellite
refrigerators, 2 compressors, the purification system andtransfer lines. The liquifier incorporates a liquid nitrogenprecooling system, 2 turbine expanders and a wet expander.
Stopped reading as paper carries on in the same way.
The cryo complex was the first one in the Soviet Union
to work under computer control. It was suggested to operate without personnel. Subsequently a few similar complexes distributed along the 21 km UNK tunnel were installed to operate only under computer control, without
any personnel. Therefore the construction of the cryocomplex aimed to not only provide the SC MTF with liquid nitrogen and helium, but also to develop and to test
the cryo equipment and the control system itself. That
stipulated features of the controls approach:• preliminary testing of control modules and application
programs using specially designed imitators for generating status and parameter inputs of the cryo equipment(temperature, pressure, level and consumption of liquid,valve position and so on)• 100% "hot" reserve of interface electronic crates;• analog electronics protection system to prevent destroying of the cryo equipment in case a break-down of computer controls;• "step by step" execution of more than 100 applicationprograms of the unclosed loop algorithms for better human control of the equipment behavior (startup andstopping of the equipment, interlocks, etc.).
The autonomous analog protection system supervises
the most critical parameters such as turbine expander
rotation frequency, pressure at vessels, level of cryo products, temperature of heat exchangers and so on. It detects
differences between preset and measured parameters. The

system uses the same pickups and actuators as the computer control system.
A control system provides surveillance of about 900
signals, management of 130 closed loops and other control
functionality.
A schematic view of the computer control system isgiven below. The architecture of the control system isbased on a two level distributed computing system. The
upper level uses MS-DOS IBM PC′s linked by Ethernet.
Every PC manages one group of equipment such as compressors, vacuum system etc. The console functions are
realized on the same PC′s.
The lower level is a set of equipment controllers (EC)in an IHEP version of CAMAC crates. Each PC is linkedby RS-232 to several EC′s. The communication protocol
provides the recognition of faults during data exchange
and the repetition of erroneous transfers thus excluding
the loss of information. The EC includes:• intelligent crate controller based on a 16 bit LSI-11compatible processor;• intelligent (16 bit, LSI-11 compatible) modules for 4
control loops aimed to provide the reliability of thecontrol system as well as of the cryo complex;• converters for the Allen-Bradley thermometers;• 12 bit ADCs;• I/O registers;• restart memory (after failure/restore) module;• thyristor and relay actuators for motors and valves.
In order to implement the software for consoles we developed a special monitor under MS-DOS which allows toorganize a multitask environment, in particular to haveaccess to several microprocessors simultaneously. The
descriptions of equipment parameters are placed in a database. A specific software is generated for each of theequipment groups, taking into account the relevant parameter descriptions from the data base version (including
upper and lower levels). This approach guarantees theinformation integrity of software for both levels.
The main functions of the software for the consoles are:acquisition and processing of data from EC′s, presentationof data as tables, graphics and charts, remote control ofprocesses, delivery of alarm messages to the operator,
protection and interlock of equipment, archiving.
The reserve EC′s are also linked to the console PC′s.
The operator can activate them replacing in such manner
the broken EC′s.
The software in the EC consists of a local problem oriented OS (home made) and a set of applications for dataacquisition, initial processing and processing of data from

Ethernet

PC
MS-DOS

Reserve

PC
MS-DOSCAMAC crates

Reserve

Technology

pick-ups for protection of equipment and interlocks, forstep by step execution of control algorithms and for exchange of information with PC′s. For step by step execution of programs a problem oriented programming language was created as macro extension to MACRO-11.
Cross compilers and relevant emulators were created on
PC to develop and test the software for EC′s.
Despite the shortage of funding did not permit comprehensive testing of the whole cryo complex, the control
system proved its reliability and provided commissioningof the cryo complex equipment and the liquid helium production under computer controls.
The author list of this status report contains only namesof group leaders. In fact many more people took part in thedesign and implementation of the control system.
References[1] The UNK Control System - V.N.Alferov, V.L.Brook,
A. F. Dunaitsev, S. G. Goloborodko, S. V. Izgarshev,
V. V. Komarov, A. F. Lukyantsev, M. S. Mikheev,
N.N. Trofimov, V. P. Sakharov, E. D. Scherbakov,
A.I. Vaguine, V. P. Voevodin, V. D. Yourpalov, S.A.
Zelepoukin and B. Kuiper, - Proc. of the Int. Conf.on
Accelerator and Large Experimental Physics ControlSystems, Tsukuba, Japan, 1991, eds. C.O. Pak,S.Kurokawa and T.Katoh, Kek Proc. 92-15 (KEK,1992).
[2] Magnet Test Facility Control System for Superconducting Magnets of UNK - A. I. Ageyev, V.N. Alferov, K.F. Guertsev, V.I. Gridassov, A.A. Gussak,
A.F. Dunaitsev, V.A. Krendelev, A.F. Lukyantsev,V.M. Proshin, V.E. Solovjov, A.N. Sytin, E.A. Ustinov, - Proc. of the Int. Conf. on Accelerator and Large
Experimental Physics Control Systems, Tsukuba, Japan, 1991, eds. C.O. Pak, S.Kurokawa and T.Katoh,Kek Proc. 92-15 (KEK, 1992).