The flexibility and robustness of a monitor and control system are a direct result of the underlying inter-processor communications architecture. A new architecture for monitor & Control at the Deep Space Network Communications Complexes has been developed based on the Open System Interconnection (OSI) standards. The suitability of OSI standards for DSN M&C has been proven in the laboratory. The laboratory success has resulted in choosing an OSI-based architecture for DSS-13 M&C. DSS-13 is the DSN experimental station and is not part of the 'operational' DSN; it's role is to provide an environment to test new communications concepts can be tested and conduct unique science experiments. Therefore, DSS-13 must be robust enough to support operational activities, while also being flexible enough to enable experimentation. This paper describes the M&C architecture developed for DSS-13 and the results from system and operational testing

Cooper, Lynne P.

Heuser, W. Randy

English

NASA Technical Reports Server

8.2 
OS1 ARCHITECTURE FOR THE DEEP SPACE ORK 
W. Randy Heuser 
Lynne P. Cooper 
Monitor & Control Technology Group 
Jet Propulsion Laboratory 
California Institute of Technology 
4800 Oak Grove Drive 
Pasadena, CA 9 1109 
ABSTRACT 
The flexibility and robustness of a monitor and 
control system are a direct result of the underlying 
inter-processor communications architecture. A new 
architecture for monitor & Control at the Deep Space 
Network Communications Complexes has been 
developed based on the Open System 
Interconnection (OSI) standards. The suitability of 
OS1 standards for DSN M&C has been proven in the 
laboratory. The laboratory success has resulted in 
choosing an OSI-based architecture for DSS-13 
M&C. DSS-13 is the DSN experimental station and 
is not part of the "operational" DSN, it's role is to 
provide an environment to test new communications 
concepts can be tested and conduct unique science 
experiments. Therefore, DSS-13 must be robust 
enough to support operational activities, while also 
being flexible enough to enable experimentation. 
This paper describes the M&C architecture developed 
for DSS-13 and the results from system and 
operational testing. 
Keywords OSI, Monitor & Control, GOSIP, Deep 
Space Network 
1. INTRODUCTION 
The flexibility and robustness of a monitor and 
control system are a direct result of the underlying 
inter-processor communications architecture. The 
Monitor and Control (M&C) system for the Deep 
Space Network Communications Complexes (DSCC) 
is based on an architecture developed 10 years ago -- 
before the advent of the international standards that 
exist today. As a result, the existing M&C 
architecture is difficult to operate, maintain, and 
update. 
The emergence of the Open Systems Interconnection 
(OSI) standards and the concept of an open systems 
architecture hold great promise for providing 
improved operational environments. The application 
of OSI-based commercial products to support inter- 
processor communications is expected to improved 
inter-operability while resulting in substantial cost 
savings. The Government Open Systems 
Interconnection Profiie (GOSIP), a mandatory 
Federal Information Processing Standard (FIPS) for 
all new computer systems, was adopted to provide 
computer security for all government systems and to 
promote the development of OS1 technology in the 
commercial arena. 
The problems that face the DSN are assessing the 
applicability of the OS1 standards for DSN systems 
and identifying migration paths from the existing 
systems to OSI-based systems. To determine 
whether the OS1 standards were capable of meeting 
the needs of the DSN, an OS1 testbed was developed 
to investigate the process control standards 
(MMS/MAP). The testbed consisted of three 
elements: the Very Long Baseline Interferometry 
(VLBI) subsystem, the power meter, and the monitor 
& control computer. The goal of the testbed was to 
establish client-server relationships between M&C 
and the two subsystems across a LAN, to create a 
client-server relationship between the two 
subsystems, and to assess performance. The testbed 
was highly successful and the results indicated that an 
OSI-based architecture was feasible for DSN Station 
M&C Pef. 11. 
The success of the OSI-based approach resulted in its 
selection as the M&C architecture for DSS-13 -- an 
experimental Deep Space Station in the DSN. DSS- 
13 is not part of the regular operational DSN. Rather, 
it serves two purposes: as a test-bed for new 
concepts in deep space communications, and as a 
resource for performing unique science experiments. 
DSS-13 consists of a new 34-Meter Beam Wave 
Guide Antenna, two advanced receivers, Weather 
Station, Total Power Radiometer, Microwave Switch 
Controller, VLBI Wide Channel Band System, Water 
Vapor Radiometer, Data Handler, and the Monitor & 
Control System. The goal for 1992 is to develop, 
install, and test an operational M&C System to 
support DSS-13 operations and experimentation 
using this core set of equipment. This paper will 
describe the architecture of the DSS-13 M&C system, 
discuss how the OS1 standards were applied, and 
provide results from systems and operational testing 
of the M&C system. 
97 
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2. DSS- QL SYS 
3) is an experimental 
communications. The core subsystems in place at 
DSS- 13 are a mixture of several generations of 
communications and radiometric instruments. The 
they all shared at the beginning of 
development was that all 
subsystems were designed to work assuming the 
presence of a dedicated operator per subsystem. The 
success of the QSI testbed activity led to the concept 
of centralized MBC at DSS-13 using OS1 standards 
and commercial-off-the-shelf (COTS) hardware and 
software. The goal set forth for the DSS-13 M&C 
team was to design, develop, integrate, test, and turn 
over to operations a centralized M&C system capable 
of supporting the Ka-Band Link Experiment 
(KABLE) using only one operator in slightly over 
one year. 
The resulting M&C system is described in the 
following section. We also present a section on our 
approach to using the OS1 standards, and the current 
status. 
to each other. A block diagram of the DSS-13 
configmation is given in Figure 1. The functional 
goals Wef 21 of the M&C system are: 
1. Provide a centralized MBC facility which 
will enable a single operator to operate all 
the equipment necessary to support KABLE. 
2. Enable the SMC operator to perform any 
operations function for the subsystem 
through the SMC 
3. Provide a means of distributing support data 
(for example, predict files) to the subsystems 
from the SMC 
4. Provide a graphical user interface which can 
be tailored by station personnel to meet their 
operational needs. 
5. Provide a means of recording and logging all 
operational functions, monitor data, and 
event notices. 
6. Provide an open systems environment 
capable of supporting automation 
JPL 
DSS-13ControlRoom B.- - - - - - - - - - 
slsco MMS-EASE 
Ms DOS 5.01 C 6.0 
RTLink 3 tinker 
Figure 1. DSS-13 Block Diagram 
I ”  
98 
Table 1. M&C Functional Requirements vs. MMS Services 
The SMC system constraints were: 
1. It must be flexible: enable new subsystems 
to be added quickly, easily, and 
inexpensively. Since DSS-13 is an 
experimental station, the ability to bring out 
new equipment, quickly connect to core 
equipment, and test out new concepts is an 
important part of its function. 
2. It must be reliable: Since DSS-13 is also, in 
a limited sense, an operational station, the 
M&C system had to be able to routinely 
support opemtions functions 
3. It must comply with the Government Open 
Systems Interconnection Profile (GOSIP) 
2.2 Approach 
The development of subsystems for DSS-13 was well 
underway when the concept of implementing a 
centralized M&C strategy at the station was adopted. 
Our approach to developing the SMC was highly 
influenced by the need to "retrofit" these subsystems 
with the capability to be operated over a computer 
network. In some cases, this was straightforward, in 
others, it required a significant effort on the part of 
both the M&C and the subsystem development 
teams. In order to remain cost effective, our design 
decisions had to work with the existing hardware and 
software environments used by the subsystems with 
little or no modification. The following sections 
describe the basic design decisions made and their 
impact on the overall system effort. 
2.2.1 MMS 
The Manufacturing Message Specification (MMS) 
protocol was chosen as the standard on which to base 
DSS-13 M&C. MMS is an application layer 
protocol designed for process control. The OS1 
testbed activity demonstrated the solid match 
between the services offered by MMS and those 
required to support M&C operations functions, Table 
1. Based on the commercial availability of products, 
the decision was made to implement the system using 
MMS over a Token Bus LAN. This decision enabled 
us to take advantage of the development work already 
done in the OS1 Testbed and to begin immediate 
procurement of the necessary hardwarel. 
2.2.2 Common Software and Environment 
Plans are already in place to replace the Token Bus 
with an ethernet. 
99 
Our approach centered on quickly standardizing a 
common language and operating system (in ow case 
DOS and MS C, current versions). These were 
sen because they several of the subsystems were 
already using them, and because 
existed for these environments. The common 
software needed b subsystem to form the 
interface between and their applications was 
developed and integrated by the M&C team. In some 
cases, this required translating from one version of 
the C compiler to another, in other cases, it involved 
finding compatible products for other environments 
(e.g. Basic, UNIX). The integration effort was, at 
times, painful due to the "after-the-fact'' decision to 
use a centr- M&C approach. The local control 
interfaces needed to be re-engineered, additional data 
structures were required to support additional 
feedback needs, and code had to be optimized to meet 
operating system memory size limitations. 
2.2.3 Data Dictionary/Table 
The primary interface between M&C and the 
individual subsystems is through the Data Dictionary. 
The Data Dictionary provides a listing of all the 
variables (used to send control information and 
monitor health, status, and performance) needed to 
run a subsystem. M&C contains a complete listing. 
Each of the subsystems contains a complete table of 
their own variables as well as additional data 
structures to provide specific information from other 
subsystems. The tabledriven nature of the 
architecture enables rapid addition, deletion, and 
other changes and makes adding new subsystems 
relatively straightforward. 
2.2.4 User Interface 
The Dexterity2 commercial user interface package 
was used to provide the SMC user interFace. Draft 
displays were generated by the SMC bam and given 
to the DSS-13 operators. They were trained in the 
use of the Dexterity package and began developing 
their own displays. In the DSS-13 environment 
where the types of activities being supported can 
change on a regular basis, it is very important for the 
operators to have the ability to tailor old displays and 
build new ones to meet their needs. Because of the 
open system architecture, data could easily be 
accessed through the data dictionary and displays 
incorporating a variety of parameters assembled 
without a software development effort being needed. 
Trademark, Nucleus Systems 
3. STATUS 
The overall configuration for DSS-13 is as shown in 
&C system is currently being tested 
with all of the major subsystems required for KABLE 
opt ions.  Development of the SMC began in 
October 1991, system integration with the DSS-13 
subsystems in July 1992, and the station will be 
Operational in order to support KAEiLE in January 
1993. During the one-year development effort, two 
new subsystems, the Station Data Recorder and the 
High Resolution Microwave Survey (HRMS) 
gateway were added. 
The HRMS gateway was developed to provide an 
interface which allowed the experiment to conml 
station equipment over the M&C LAN when the 
previously planned direct connection was deemed 
unfeasible at the last minute. The subsystem was 
developed, integrated, and tested in under 4 months 
and supported the HRMS kickoff on October 12, 
1992. The flexibility of the DSS-13 M&C 
architecture in responding to a short fuse customer 
request resulted in a successful experiment. In 
addition, the DSS-13 operators developed a display 
which allowed them to monitor the station equipment 
while it was under the control of the experiment and 
were able to detect a serious anomaly in time for the 
experiment to f i i  it during the actual experiment. 
4. SUMMARY 
The DSS-13 experience in the application of OS1 
standards to support M&C has been extremely 
successful. The chosen standard, MMS, meets the 
functional needs of the station and provides a level of 
flexibility and responsiveness previously unknown in 
that environment. The architecture is robust enough 
to meet current operational needs and flexible enough 
to provide an migration path for new subsystems. 
The experience has also highlighted some important 
lessons learned on the application of COTS hardware 
and software and the importance of good systems 
engineering and configuration control. As a 
"breadboard" for a M&C system for the operational 
subnetworks of the DSN, the DSS-13 M&C System 
has provided valuable insights and a proof of 
feasibility for the overall architecture. 
5. ACKNOWDGMENTS 
The work described in this paper was carried out by 
the Jet Propulsion Laboratory, California Institute of 
Technology, under contract with the National 
Aeronautics and Space Administration. In addition to 
the authors, the DSS-13 M&C development team 
includes Mike Stockett, Richard Chen, Lyle Skjerve, 
and Bob Gosline. We would like to extend ow 
appreciation to the numerous DSN operations and 
engineering personnel who have contributed to this 
effort, and especially Gerry Crook, Ron Littlefair, 
and Mark Gatti. 
6. REFERENCES 
1. Heuser, W. Randy, "An OS1 Architecture for the 
Deep Space Network," Jet Propulsion 
Laboratory TDA Progress Report Volume 42- 
109, Pasadena, CA, January - March 1992. 
2. Gatti, Mark S., and Lynne P. Cooper, "DSS-13 
Conceptual Functional Requirements," JPL 
Internal Document IOM 3320-91-054, Pasadena, 
CA, February 6,1991. 
7. ACRONYMS 
COTS 
DSCC 
DSN 
DSS 
FWS 
GOSIP 
HRm 
I S 0  
KABLE 
LAN 
MAP 
M&C 
MMS 
os1 
SMC 
TDA 
VLBI 
Commercial Off the Shelf 
Deep Space Communications Complex 
Deep Space Network 
Deep Space Station 
Federal Information Systems 
Processessing Standards 
Government Open Systems 
Interconnection Profile 
High Resolution Microwave Experiment 
International Standards Organization 
Ka-Band Link Experiment 
Local Area Network 
Manufacturing Automation Protocol 
Monitor & Control 
Manufacmhg Message Specification 
Open Systems Interconnection 
Station Monitor & Control 
Telecommunications and Data Acquisition 
Very Long Baseline Interferometry 
101 


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