Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
A.~.4 Computer Considerations in Communication by MatlLx Corporation Raleigh, North Carolina Background New transportation management strategies require the capabilities of modern computer systems. In the past, highway corridor control systems used mainly Model 170 or NEMA controllers; however, new intelligent highway applications require more traffic monitoring and processing than before. This need has created demand for what is commonly referred to · : ; : .,. , ,,-.; , I. , ~3 [. . ;............ .,.? ,:,2:'::.:.',.,., ,: _ ,., ~. ~ , ; ,;, ~.~.~:C~:~;::;~; OWN '. ':.::, ;,~r.;.~,~.;, ; .; .; · ;. .; ;; .. ;; ~ " " , ,' ' ''' ' '' , ' ' ' ' :: ' " .' . : ' " ~'. ' ' ' ' . ', ': ' ' ', ' :, ' ., " '",:'' ' ' ' ' ' ': ' ' :'.: '':':' ' "' ': ' '" "'""'"' '" '' "'".''"" ~ ":' ' ' "' '. :'. ;:: "' ' ' ' ': ' . '"''' " ' """' "' . . . i. ' ''' ' ' ' "' ' ' ' """'"'"' """' "'"'e' ' """".' "' """" ' ""'"""" """""""""' """"' '''i''' '".,2.2.22 2'"2. , ~ ~ ~:.,.,:,,':,.',.2' ''""''""'."""""'"'""""'~''""""''e'~'~'d'.' .,, '.,. 't,,,.~.t ~' ,,2:.'.' '.'"' ".2:""'' '' '' 2 "'2 . ' , ' ", 2 . .,2 . '"2 '' 2' ' ,'.'' 'l.'",.' .. '.. .2.'2 '.. "..2 . "'."'"' 2",','" :'. .'.,"""2,.,2.,.,2,'2:,.,."2222". ""2"2 ',., ',',. 2 '' '' ',. 2,2 ,;,2 ,.": '.: .." 2l '.:.'' .2 ' ~'.' ' ~.'.. i ." . 2 . 2 .... 2 . 2 2...2.. ~ i::: . :,:,:::: :'. '.,'.:.,..,:,.: . 2 '.:':....2.:...................... ........ , ,,, . ,,,., ,,, ,, ,, ,,, . ,,,,,,,,,, i ·, - am-: - ...... ,,,,. . . , .: , :.: : ' ::::: ~ ' : . : Or:::::::::: :::::::::::::: :::::::::::::::::::::::::::::::: ::: :: :: : . .... .. ..... .. . .. .......... : . . .: .:: Figure A.1.41 Example VICE bus-based 2070 controller for ITS as an Advanced Transportation Controller (ATC). As a result, ATCs are now being deployed in highway applications In ever-increasing numbers. What Is an ATC? The definition vanes, since its functional characteristics often differ from one application to the next; however, there are severe common factors to the new generation of ATCs: · A VME computer bus (a nonproprietary computer bus structure) ~ Operating temperatures of -34° to +74°C · Off-the-shelf real-time operating system (e.g., OS-9. L..\NCHR~Phasc2.1pt\2070.qx ~NCHRP 3-51 · Phase 2 Final Report A1-190
The 2070 An Open Architecture VMEbus-based Advanced Transportation Controller Overview/App/ications The 2070 is an ATC conceived by California Department of Transportation (Caltrans), the City of Los Angeles, and others to provide distributed computing, control, and communications within traffic infrastructures. It conforms to the comprehensive Transportation Electncal Equipment Specifications (TEES) developed by Caltrans. The 2070 not only augments the role of traffic operations centers, but it also provides features and functionality not provided by previous generations of traffic controllers. The ............ .................... ..- ... ., ..., ,...., .... ,..- .......... ,........................................................ , . ............................ ,. ... . , . ............................ , . . . . ......................... , .............. . ................................................................... . . ............................ ........................................................... Figure A.1.42 MC68360 OPUS He 2070s VMEbus Card Cage 2070 is built upon a nonpropnetary, configurable, open architecture computer platform that accommodates a wide range of functional modules. These modules (plug-in computer boards) conform to the well-established standard VMEbus specification. The VMEbus specification defines mechanical and electrical characteristics to establish compatibility from one manufacturer to another. The selected combination of modules and applications software determines the functionality of an 2070. Two basic configurations are available to ensure 2070 compatibility with existing NEMA and Mode} 170 controller cabinet standards: Me TS3 and the 2070 respectively. The 2070 supports sophisticated applications such as adaptive intersection control, integrated corridor management, emergency surveiliance/pre-emptive management, emergency call box communications, etc. i Its expandability allows it to control many more devices than older controllers. A single 2070 can control several ramp meters, speed monitors, and changeable message signs (CMS), in addition to environmental sensors and cameras. ~ previous highway designs, each function required a controller. Also, video processing modules can be instaNed In the 2070's VMEbus. These modules detect and determine speed, ciassiDcation, and travel time from one controller point to another. See page 4 for an example system configuration where the 2070 is cast in the role of Intelligent Multiplexer. r - ~ ~ L:WCHAP\Phase2.rpt\2a70.qx ~NCHRP 3-51 · Phase 2 Final Report A1-191
With the 2070, contractors have fewer cabinets and communication lines to install which streamlines project requirements. Aside from lower installation costs and shorter deployment schedules, an 2070 installation is also simpler for the DOTs to maintain. Major Subsystems of the 2070 VMEbus/Computer Platform (see Figures A.~.4-] ar'`A.~.4-2) This platform provides the brains that coordinate other 2070 subsystems and manages the key 2070 functions-control and communications. It incorporates a computer processor module resident in art expansion chassis that provides four expansion slots for other functional modules. The combination of modules in an 2070 is user selectable to manage the applications at hand. The computer module incorporates a high-speed 32-bit computer chip. It integrates advanced communications capabilities such as SDLC, HDLC, Ethernet, etc., and can connect to T! telecommunications lines. Its features support high bandwidth communications . Front Panel The 2070 front pane! assembly consists of two keypads and a 4x40 LED display managed by a dedicated microprocessor for high display update rates. The interconnection to the main V~bus processor is a serial differential interface which provides electrical protection. Fred Inpu!JOu~ut Module Field I/O Modules for the 2070-170 and 2070-TS3 are different in format but provide the same functionality: the interface to to load switches and detectors. Like the Front Pane] Assembly, the Field I/O Module incorporates a dedicated microprocessor. It provides pre scanned or pre-collected input data at rates of 1,000 samples per second without interrupting the primary VME control processor. ~2 2070-7 EIA-232 Module (I t2 lo. 2070~ Modem Modu~e (I · ~, · T: it _T 2070-1 Trar~on Module 2070-1 CPU Module , ,, ., l. ' Tonal it, Optional it, Optional it, Optional ~ VME , ~ VME , · VME I · VME W ·. ·. .. 88 18 18 ~.' 81 ~ ~ i, ,, 2070~2 OR 2070~8 weld TO Module ... .. . 1 . ~ ~ ~ EIA Data ~ , 485 Key 170 C1 & C11 Connectors OR Name MS A, B. C, & ~ Connectors L:\NCHRP\Phasc2.rpt\2070.qxd 4x40 1 LCD Dam I ~ ~ LIP 11 1 11 Eu Poll 2070~ 1~0 Front Panel NCHRP 3-51 · Phase 2 Fmal Report DC Loo Po_ t t 2070- Power Supply t AIC FgureA.1.43 2070 Architecture A1-192
2070 Modem Module This module provides the communications link between the traffic operations center and remote 2070s which might be acting as regional communications hubs to concentrate, pre- process, and communicate data from multiple intersections, etc. System modularity allows for older Bell 202 modems, as well as higher-speed modems and fiber interfaces (including DO-. One modem module may be interchanged for another at any time. 2070 Communications Module Two general purpose senal channels are provided. They can be configured as ElA- 232/422/~85 and over electrical interfaces. Software The 2070 real-time environment is based on OS-9, an industry standard operating system. The 2070 incorporates diagnostic and various self-test software. Application software is not integral to the 2070. Rather, application software is available from specialized software suppliers, integrators, consultants, and DOTs. Maintenar~ce/Rel~abitity Since the 2070 is modular, it enjoys the efficiency of a board-swap maintenance regimen. The 2070 is designed to operate in harsh environments from -34° to to +74°C. Software changes/upgrades are performed by serial downloads, elilIiinatirlg Me need to handle the elc~onics. Thus, one of the primary causes of failure "handling" is eliminated. Table A.~.4-1 Requirements versus Capabilities of Various Controllers Features NEMA MODEL NEMA 2070 TS-1 170 TS-2 Industry stanclard, open architecture computer No Yes No Yes Based on openly available real-time OS No No No Yes Use of high-level languages No No No Yes Powerful microprocessor . No No Yes Yes Ability to support T1 communications rates No No No Yes Expandabiltyof number of 1/0 points No No Yes Yes Ability to support NTCIP No No Yes Yes Modular architecture for maximum flexibility No No No Yes Scalable for future growth & technical advances No No No Yes L.\NCHRP\Phase2erpt\2070.9xd NCH~P 3-51 ~Phase 2 Fmal Report A1-193
Example Application The 2070 as an Intelligent Multiplexer TOG Computers Ethemet Figure A.1.W 2070 in He Role of Intelligent Multiplexer ElA-232 Multidrop ~ Modems to Intersection _ _ . .. 2070 ^ ~ is IMUX ~ Controllers& Other Devices USA Router . . EIA-232 Multidrop DS-1 2070.4 . ~ Modems to IMUX ~Intersection Other Devices ~1 1 EIA-232 Multidrop 2070 ~ ~ Modems to IMUX ~ Intersection Controllers & Other Devices ATCs are often thought of as field processors that can only "control" traffic devices. How- ever, ATCs are much more capable and can be applied in applications calling for fi~nction- ality beyond the capabilities of NEMA or Mode! 170 controllers. This example demon- strates a system configuration where the 2070 plays a key role in providing powerful communication capabilities econom~caDy. Communications is a critical element for most ITS applications. In many modern ITS designs, communications paths run from computers in a traffic operations center (TOC) to a router. The router's main purpose is to route and exchange data between the office network (e.g., Ethernet) and an external telecom interface (e.g., DS-1). From there, data is transferred to 2070s that perform an Intelligent Multiplexer function and are positioned regionally. The 2070 Intelligent Multiplexers route data to the actual devices (e.g., intersection controller, CMS signs, etc.), often over multidrop modem interfaces. This example is significantly different from simpler point-to-point communications methods. This design minimizes wiring from the field and the ability to use open architecture standards such as ATCs, telecommunication interfaces and equipment, office networks, etc. Additional benefits include lower maintenance costs, simpler installation, and better reliability. This architecture is also adaptable to future requirements. For example, it can be used for new adaptive intersection condom algorithms Hat use distributed architectures and require significantly enhanced communications capability. L.\NCHRP\Phase~rp~O.qx ~NCHRP3-51 · Phase2FinalReport A1-194
User Acceptance and Demand Several Integrators have deployed open architecture computers In traffic management applications over the past eight years. Many of these systems were configured from VMEbus modules running off-the-shelf real-time operating systems, like OS-9. Most of these initial deployments were for highway control and toll applications,where capabilities beyond those offered by the Mode] 170 were required. Over the last two years, a ground swell has taken place toward ATCs. Caltrans has spent considerable resources developing the 2070 specification, and the 2070 is intended to be the next-generation controller for Caltrans' rRs applications. Interest in ATCs has grown so strong that U.S. DOT's Transportation Research Board (TRB) has set up a task force to track MC developments and disseminate information. ATCs are now being deployed In highway management, toll collection, intersection control, and other transportation applications. ~:WCHR~Phase2rprs2070.qxa NCHRP 3-51 · Phase 2 Final Report Al-l9S
