What do photocopiers, roller coasters, heart-monitoring equipment, race cars and power utility machinery have in common? Each of them uses a recorder or datalogger to track and display events as well as help determine the cause of problems that interfere with optimum performance.
Recorders and dataloggers are available in a variety of technologies such as pen and ink chart and electronic versions, data acquisition systems and test instruments with datalogging capabilities. Applications are extensive and include most industries that need evaluation of output waveforms, performance testing and monitoring.
The common recording technology of a decade ago was the ink-and-paper analog amplifier-to-pin servo unit. Datalogging was represented using scanning analog-to-digital (A/D) converters which sent data to some form of memory media, such as battery-backed RAM or disk drive. Many of these instruments are still used today.
But recorder technology has progressed dramatically in the last 10 years. Today’s recorders include hybrid instruments that scan and store information to memory like a datalogger and present it on a color monitor. Dataloggers are often linked to a PC for post-processing and data analysis and use the PC monitor for real-time viewing of the information.
Many technological advances have prompted manufacturers like Yokogawa to create a hybrid recorder that is six times smaller than previous versions. The company developed a high-breakdown voltage solid-state relay (SSR) that switches the inputs when performing multichannel measurements. The SSR takes the place of the contacts and drive parts of a mechanical relay, overcoming the problem of defective measurements caused by faulty or worn contacts on mechanical relays.
Another part that reduces the overall size of the recorder is the planar transformer. This small transformer consists of a multilayer thin-film coil that reduces heat and noise emissions compared to a conventional wire-wound transformer. It reduces the volume of the power supply unit from one-half to one-quarter the size of previous power supply units.
Trends
The ‘90s ushered in a love affair with the PC, making it the pen, pencil and calculator to the engineer, said Paul Gannett of Keithley MetraByte. The PC performs all the necessary data manipulation functions quickly and easily and connects to other instruments such as the datalogger.
Datalogger users consider the PC an integral part of their data-gathering and manipulation process because it can import data as well as analyze and display it. The PC performs these operations within the confines of present software packages, including spreadsheets and word-processing packages.
The advent of the notebook PC adds another capability to datalogging. It allows you to carry instruments into the field, analyze results on the spot and make real-time adjustments, said Mr. Gannett. In these applications, using a PCMCIA card is advantageous because it is small and costs about $600 for a card with 16 analog inputs.
If your application is in a severe environment, the PC is not the best instrument. A stand-alone datalogger is usually more rugged than a PC, said Mr. Gannett. Typically, the information is downloaded to an office PC for analysis via a direct RS-232 link or a modem. The modem allows data to be retrieved over the phone lines without sending anyone into the field.
Another trend for dataloggers is the increase in sampling speeds. For example, more powerful microprocessors and digital signal processors commonly sample data at speeds up to 1,000 kHz, said Chris Dobson, President of RCC Technologies. Support chips, such as A/D converters and rms converters, are also faster.
The direction for recorders, however, is closely tied to the improvement of color display technology, said Bruce Fuller, Senior Product Specialist at Fluke. Many manufacturers are replacing the chart paper with sophisticated color displays. Other companies, unsure of the direction, offer both.
Display technology, coupled with high-accuracy A/D converters, 32-bit microprocessors and ample data storage capacity, places paperless recorders in the same price range as paper recorders, said Paul Coughlin, Product Manager of Monarch Instruments. By removing the paper medium for data storage, you save material, storage and time required to review the measurement data.
Although the transition to the PC has started, not everyone is ready to lose the paper, said Brad Byrum, Marketing Manager of Yokogawa. Regulations in some industries still require a chart recorder and many customers still want the paper-type recorders. If you use a PC, however, a direct connect to the PC via an interface such as RS-232, RS-422 or GPIB will help you measure data directly and avoid using paper.
The growth in the recording market is in the high- and low-end product sections, said Perry Moss, Marketing Manager for Metrum. At the high-end, recording demands continually increase due to a need for higher resolution and more data points. The low-end growth includes commercial off-the-shelf boards that plug into existing computer platforms.
Recorders/Dataloggers
Recorder Connects Directly
To Rack or Bench System
The AstroGRAPH Recorder is an option for the company’s AstroDAQ data acquisition system, available in a rack-mounted or benchtop enclosure. The recorder print engine uses direct thermal technology for use before, during or after data acquisition. The unit supplies up to 30 channels, a chart speed to 100 mm/s with an accuracy of ± 2%, and a paper capacity of 80 meters or 400 individual sheets. A digital interface connects directly to the AstroDAQ system. Functions include real-time charts, data logging, capture playbacks and ASCII text. Rack-mount: $3,995; benchtop: $4,295. Astro-Med, (800) 343-4039.
Clamp-On Power Datalogger
Stores 1,000 Readings
The Model 382060 Clamp-On Power Datalogger measures power without interrupting circuit connections. It displays true rms volts, amps, power factor, watts, minimum/maximum and average readings. The datalogger stores 1,000 readings for unattended monitoring. An optional RS-232 module allows transfer and display of data on a PC. $599. Extech Instruments, (617) 890-7440.
System Monitors 20 Channels
At 1,000 Readings Per Second
The NetDAQ™ 2640 Series of networked data acquisition tools accepts 20 input channels and links up to 400 channels. The system includes a Windows™-based package for plotting functions. The 2640A provide a measurement speed of 100 readings per second (rps) with 5« -digit resolution and 0.01% accuracy. The 2645A has a measurement speed of 1,000 rps with 4« -digit resolution and 0.02% accuracy. Any combination of DC or AC voltage, thermocouples, 4 to 20 mA, RTD, resistance or frequency are sent to the input module. Starts at $3,995. Fluke, (800) 443-5853.
Recorder Stores
Up to 102 MB Data
The PANTHER Model EDR-4 Series Recorders are self-contained, user-programmable acceleration sensor and recorder units. The 5-lb unit accommodates remote stand-alone shock and vibration measurements and recordings from several hours to many weeks. It features a built-in piezoresistive triaxial accelerometer; 12-bit, 15-kS/s digitization per channel; and storage to 102 MB. The battery-powered unit has a real-time clock and a 110k-baud serial and parallel-port data interface. The recorder acquires data on three or six channels simultaneously. Instrumented Sensor Technology, (517) 349-8487.
Scanner Card Adds
Two-Pole Measurement Capability
The Model 2010 Multimeter offers a self-contained multipoint measurement system, using a 10-channel scanner card. The card inserts into the instrument’s option slot, providing 2-pole relay inputs. The meter has a 100-nV noise floor on the 100-mV range and performs 2,000 measurements per second at a resolution of 4« digits. It offers 15 measurement functions, including voltage, current, resistance, temperature, frequency, period and diode testing. $2,395. Keithley Instruments, (800) 552-1115.
Solid-State Datalogger
Supports Analog/Digital Inputs
The Datataker 605 is a solid-state datalogger that operates independently of a computer. It provides 10 differential and 30 single-ended analog inputs, four TTL/CMOS-compatible digital I/O channels and three high-speed counter channels. Data is downloaded via an RS-232 interface, a modem or a radio link, or with a memory card. A battery-backed RAM card stores 13,650 readings and a Type 2 PCMCIA card stores an additional 34,000 readings. The unit measures voltage, resistance, current, frequency, current loop, period and temperature. $3,295 Keithley MetraByte, (800) 348-0033.
Portable Datalogger Has
Windows™ Setup Function
The Hyperlogger™ Portable Datalogger uses Windows™ to perform setup and data analysis. The icon-based programming software configures channels and sampling rates, sets alarms and control functions, manages signal processing and defines data-collection properties. The unit has programmable filtering, 13-bit analog-to-digital conversion and a 100-S/s rate. It has six ports for plug-in interface modules, 24 mixed analog or digital inputs, and multiple alarm outputs. Data is stored in battery-backed RAM or in a removable PCMCIA memory card. Communications is via a modem or RS-232 port. Starts at $2,680. Logic Beach, (619) 698-3300.
Digital Recorder Offers
Variable Data Transfer Rate
The METRUM Variable-Speed Digital Recorder 64 provides transfer rates to 64 Mb/s and burst rates of 160 Mb/s. The unit stores 27.4 GB on an ST-160 half-inch tape cassette and 20.8 GB on an ST-120 tape cassette. The record time ranges from 57 min @ 64 Mb/s to 122 h @ 500 kb/s on an ST-160. The error performance is better than 1 in 1011 bits. An on-board data buffer enables speed matching, reproduction of data at rates different than recorded and data transfer within 5 ms. A microprocessor-controlled servo system controls tape handling. $64,000. Metrum, (303) 773-4700.
Paperless Recorder Supports
Six Analog Input Channels
Data-Chart® 3000, a paperless recorder, supports six analog inputs and displays an additional six computation channels on a 5″ LCD. Analog input modules accept a variety of DC voltage and current, thermocouple, RTD and pulse signals. Data is stored on an internal buffer and simultaneously on a PCMCIA card or a floppy disk. Dedicated Windows™ software provides file management and printer support, and enables file export via addressable RS-485 or RS-232 ports. The unit computes and displays multiple math functions and provides 48 internal alarms. Starts at $1,325. Monarch Instrument, (603) 883-3390.
Portable System Works In
Harsh Environments
The MicroPro System is a multichannel portable data acquisition system used in remote operations and harsh environments. It combines high-resolution digitizers, built-in signal conditioners and digital-event channels. Data is sent to a PC via a twisted-pair fiber-optic link or via wireless RF transmission. The system mainframe operates in a range from -40° F to +185° F and is made of nickel-plated aluminum. It meets MIL-STD-810E requirements for 10-g half-sine shake and 100-g shock applications. The mainframe includes a power module, a communications interface module and a PCMCIA card. Starting at $12,500. Nicolet Instrument Technologies, (608) 276-5600.
Datalogger Calculates THD
And Performs RMS Conversion
The Inter Volt Analyzing Datalogger calculates total harmonic distortion (THD); measures rms voltage, frequency, first through 15th odd harmonics and out-of-limit events; and captures waveforms. The unit catches up to 300 user-defined events with a duration of a half cycle or longer. It is powered by the line it measures from 75 V to 750 V, and has a 3 A/h battery and a lithium battery. The storage rate is selectable from 1 minute to 60 minutes with a sample rate of 250 m s. The datalogger stores up to 30 days of readings. $2,865 RCC Electronics, (800) 733-4722.
Datalogger Has 16 Input
And 16 Math Channels
The Rustrak Ranger IV supports 16 input and 16 math channels. Universal input modules accommodate DC, AC, thermocouple, RTD and RH measurements. The input boards are supplied in four-channel groupings, up to 16 channels, in an isolated or a nonisolated design. The base internal memory is 512 kB with an option for 1 MB. Applications include monitoring and troubleshooting motors and process variables as well as temperature and RH profiling. Starts at $1,745. Rustrak Instruments, (800) 332-3202.
Flatbed Recorder
Monitors 20 Tests
The Model 606 Multicorder supplies portable flatbed chart recording as well as real-time monitoring via a built-in 3.5-digit LCD display. Readouts include measured value, polarity and overloading. Battery- or line-powered, the unit monitors and records 20 test ranges on a recording width of 100 mm. It accommodates both roll and single- sheet paper formats plus standard and waxed inkless paper. A disposable felt pen, a refillable ink pen or a sapphire stylus for waxed paper is available. The recording speed is 20 cm/s with a response time of 0.5 s. $1,665. Simpson Electric, (847) 697-2260.
Recorders Have Combined
Voltage/Temperature Module
The DCR-540 and DCR-520 Digital Chart Recorders are equipped with combined voltage/temperature modules. The DCR-540 has four channels, a pen offset compensation, an internal trigger for dual chart speeds, an alphanumeric plot of instrument settings and digital servos. The DCR-520C offers up to eight channels, and contains all the features of the DCR-540 plus an IC memory card, a real-time clock and input modules for voltage, temperature and true rms. DCR-540: from $3,635; DCR-520: from $6,425. Soltec, (800) 423-2344.
Data Recorder
Provides 64 Channels
The PC216Ax Data Recorder supplies up to 64 channels of synchronized recording for up to six hours. The portable instrument features normal- and double-speed record and playback from DC to 20 kHz. It provides signal monitoring, data acquisition, band and channel switching, and digital I/O. The recorder automatically compiles information about every recording session on the leading two-minute area of the tape. It uses a 16-bit linear quantization enabling a dynamic range >80 dB. The unit operates on AC or DC power. $21,200. Sony Magnescale America, (714) 921-0630.
Recorder Software Supports
Real-Time Monitoring
QuikVu RX™ Software is used with the company’s RX-800 Data Recorder Series for real-time data monitoring. It helps set triggers, preview information, capture data samples and monitor data while recording. Analytical functions include averaging, rms, maximum/minimum, frequency analysis, histogram, differentiation, integration, filtering and correlation. The software enables data transfer from the recorder to a PC in either a binary or an ASCII format. The RX-800 series units can record 16 channels for 1 h at DC to 20 kHz or 32 channels at DC to 10 kHz. $2,000. TEAC America, (213) 726-0303.
Analog Recorder Has
34 Chart Speeds
The Series 4500 Micoscribe is an analog strip chart recorder with 34 chart speeds and 18 sensitivity ranges starting at 1 mV. The servo system uses a capacitive rebalance transducer and offers a 0.25-s response time. A microprocessor controls all functions and drives the LCD status window. Chart speeds range from 1 cm/min to 60 cm/min and 1 cm/h to 60 cm/h. A standby battery powers data memory for 100 h. $1,295. The Recorder Co., (210) 629-1400.
Data Recorder Stores
64 Channels to PCMCIA Card
The T-Corder Model 512 Solid-State Data Recorder analyzes analog, pulse and state signals, and stores the information to a PCMCIA card. It stores up to 64 channels at 12-bit resolution. Signals such as voltage, temperature, pressure, strain, rotational speed, pulse counts and switch positions are recognized. The unit operates from an external unregulated DC supply and provides an isolated, regulated 5-VDC source. It includes DOS software for real-time communications. $2,495. Vulcan Enterprises, (602) 759-1600.
Portable Hybrid Recorder
Measures 300 Channels
The DR230 Hybrid Recorder is a portable unit that can measure data from 10 to 300 channels in 500 ms. Input modules can measure temperature, DC and AC voltage, flow rate and strain. DR230 records and transfers data simultaneously to a PC or stores information on an optional 3.5″ floppy or PCMCIA card. $2,790. Yokogawa, (800) 258-2552.
Real-Time Math Option
Computes Virtual Signals
The Live!View System is a real-time math option for the company’s TA11 and TA6000 Data Acquisition Thermal-Array Recording Systems. Live!View replaces external specialty signal conditioners, computes virtual signals, and provides results in real-time. It performs calculations at up to 50,000 S/s per channel, uses up to 200 characters per equation, and performs simultaneous integration on 16 channels. The option allows you to redefine the characteristic of a signal conditioner on the fly. Applications include automotive engine dynamics, machine diagnostics and biophysical monitoring. From $995. Gould Instrument Systems, (216) 328-7000.
Copyright 1996 Nelson Publishing Inc.
September 1996
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