PC Based vs Stand-Alone

Operation is COMPUTER- DEPENDENT

Power interruption or software crash halts monitoring and control

Completely STAND-ALONE to ensure maximum system uptime; when multiple units are networked, each node operates as an independent stand-alone system

All data acquisition and control functions TRANSPARENT TO THE COMPUTER and continue without loss of configuration or data when the computer is down

Specific cards limited to particular transducer types and ranges

FIXED ARCHITECTURE: The system is tied to a specific computer platform, and requires upgrading with each new computer generation (high potential for rapid obsolescence)

Accepts mixed inputs from VIRTUALLY ALL TRANSDUCERS for an exceptionally wide range of measurements

Interfaces with VIRTUALLY ANY COMPUTER under any operating system and programming language; positioned for compatibility with new computers as they become available

OPEN-ARCHITECTURE LINKAGE makes real-time and historical data accessible via computer-independent third-party software (Autonet, Labview, Lab Windows, Paragon, etc.)

Depends on available computer hardware and software resources; often requires multiple vendors and extensive programming

Data displays are dependent on software; simultaneous display of multiple screens normally requires multiple computers, while display modifications usually require halting the process and reprogramming

Standard operating firmware means NO PROGRAMMING: Simple English mnemonics initiate user-selected setup and run-time functions; the system can be up and running in a very short time

SINGLE VENDOR, single responsibility

Larger systems support MULTIPLE INDIVIDUALLY CONFIGURABLE DATA DISPLAYS with adjustable update rates; display formats may be created or modified by the operator even while the measured process is running

Depends on available computer expansion slots (even with an expansion chassis, you can quickly run out of slots!)

Addition or replacement of cards entails opening the computer--and all the risks associated with this action!

INDEFINITELY EXPANDABLE through addition of mainframe racks and/or networking of individual "on-site" units

Quickly and easily RECONFIGURAIBLE IN THE FIELD, with no computer programming; cards can be added or replaced WITHOUT TAKING THE MAINFRAME APART

Special transducer connection panels often required, with difficult access and cable hookups

Proximity to process sensors limited by computer location and power source; usually requires a maze of cables back to the central computer

DIRECT TRANSDUCER CONNECTIONS from rear of instrument, allowing quick disconnect while on-line

Remote data collection and control units can be located CLOSE TO PROCESS SENSORS, greatly reducing costly and troublesome cable connections

DC-powered units for vehicle operation

Built-in troubleshooting typically not available

BUILT-IN HEALTH MONITORING

System modularity and ease of access facilitate RAPID DIAGNOSIS AND REPAIR

ALL DATA PROCESSING PERFORMED BY THE COMPUTER; this restricts the computer's time and ability to perform other critical tasks, while adding significantly to the total software overhead and programming demands

Critical control response time is difficult to determine because of variable processing speed and other factors

SUPPLIES THE HOST COMPUTER WITH FINISHED ENGINEERING-UNIT DATA WHEN (AND ONLY WHEN) REOUESTED SO ALL THE COMPUTER NEEDS TO DO IS ASK FOR IT

PROCESSING FUNCTIONS include automatic conversion to floating-point format; maintaining individual multichannel data displays; archiving and playback of historical data; limit checking and alarming; linearization and calibration; cross-channel calculations; analog and digital control outputs (including high-frequency analog output and PID loop control) with precisely determined response times; counter/timer functions; on-line SPC; repon generation; and much more--all completely independent of the computer

WITH CONVENTIONAL PC'S, YOU TRADE OFF SOFTWARE OVERHEAD FOR FINISHED-ANSWER THROUGHPUT

Unless you're exclusively interested in high-speed dynamic analysis, a fast sampling rate yields "raw data" only; to produce an acceptable "finished answer rate--especially when a large number of channels must be processed--typically consumes 25% to 100% of the PC's time and resources, and also has an adverse effect on the screen update rate

FINISHED-ANSWER PROCESSING (INCLUDING DATA DISPLAY AND REAL-TIME PROCESS CONTROL) MAKES NO DEMANDS AT ALL ON THE HOST COMPUTER

For systems with over 60 measurement inputs or with complex calculations, throughput of finished-answer data is typically FASTER than the comparable PC-based system--and this includes computation of true average of highly dynamic variable--with no display update delay

Electrically noisy environment limits accuracy of sensitive input signals and the reliability of associated control functions

Sampling of dynamic signals with unrestricted input bandwidth can produce significant aliasing errors

Lack of specific calibration functions requires user to improvise his own techniques, thereby introducing overall measurement inaccuracies

Features the proven reliability of TRUE ANALOG SIGNAL CONDITIONING, with accurate, remotely sensed excitation and with separate amplifier, 3-pole filter, and selectable digital filter for each input

LOW-NOISE FRONT-END ENVIRONMENT ensures drift-free measurement and dependable control action

Optional synchronous data collection yields VIRTUALLY ZERO TIME SKEW

Accurate BUILT-IN CALIBRATION for a wide variety of sensors