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The software
The CAT200 software, developed by National Instruments, Austin, TX, exclusively for Tektronix, is the first product to use DOS-based virtual-instrumentation software technology acquired earlier this year.
A mouse is used to activate any control or to acquire any waveform with this software. No programming experience or formal training is required to use the software.
The combination of the software and the digital capabilities of the scope make for virtually hands-off operation. Front panel setups can be stored on the PC be fore going to the field and then called up as needed. The software can display up to six waveforms, which can be stored for later analysis or compared with incoming signals. A permanent library of reference waveforms can be created on a hard disk.
A feature of the software is its built-in support for Hayes-compatible modems.
A modem links a PC to an oscilloscope wherever phone lines exist and, in effect, turns the telephone networks into the world's longest probes. Simple controls and menus provide for direct dialing of modems from the software. Once connected, a user can control the oscilloscope as if it were on the benchtop next to the computer. Captured waveforms may be uploaded or downloaded to and from a remote field site and a main station. The waveforms can be displayed on the PC or stored to disk for later analysis.
The software also expands the capabilities of the scope. Delta cursors can be used to automatically measure voltage, time and frequency of acquired signals.
The system can output hardcopy to more than 80 popular printers.
In conjunction with developing the software, National Instruments developed a 222 instrument driver for its LabWindows instrumentation software. In addition to controlling the scope, the instrumentation software driver will read in waveforms stored to disk with the CAT200 software, where the data may be further analyzed and reduced.
Based on info furnished by Tektronix.
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Bench servicing has one major advantage over field servicing: If you run into something you've never seen before, such as an unusual waveform, you can show it to the rest of the techs. Some one else in the shop might have seen the waveform before and could advise you.
However, when you're in the field, you might have to make a series of telephone calls to the service center, attempting to describe the questionable waveform or condition. When that fails, you can transport pictures of the scope's display or saved waveforms back to the center in a last-ditch effort to solve the problem. Of course, if you're servicing someone's computer system, the company might be a little upset about not being able to access important information for an extra day.
Tele-servicing provides a better way.
The combination of a proper oscilloscope, a modem-telephone link and a personal computer is bringing the benefits of tele-servicing to field-service applications. Instead of a single person grappling with a difficult problem, the technician can call on the substantial resources of the service center. Field service becomes a team effort that includes the technician in the field and the often more experienced service-center engineers and staff. In effect, less experienced techs can access the expertise of highly trained technical experts over the world's longest "probe" - the tele phone line.
One system that makes tele-servicing possible is the Tektronix 222 hand-held digital storage oscilloscope (DSO). placed at a remote site and linked by modem to a service center computer.
When the oscilloscope is coupled with a personal computer and the CAT200 Virtual Instrument software, the technician has a graphical user interface that mimics the oscilloscope's front panel on the PC's screen. An engineer or technician who is trained and experienced in scopes will feel immediately at ease with the familiar front-panel controls on the PC's monitor. Because the scope is programmable, the engineer can set up and control the scope from the PC with out knowing programming or other computer technology.
Faster troubleshooting
The sooner critical waveforms are interpreted, the faster a problem can be solved. When the technician can send waveforms directly to experienced engineers in the service center, the troubleshooting task becomes faster and easier. In fact, the scope sends waveforms over the modem virtually in real time.
Problems that often took days to diagnose can now be solved in a few minutes. In effect, the oscilloscope exceeds its role as a test and measurement tool and becomes a powerful communications tool that links the problem in the field to the solution in the service center.
Reference libraries
Tele-servicing also makes it possible to build reference libraries of waveforms at the service center. These waveforms will facilitate troubleshooting and are useful in documenting the performance characteristics of the equipment being serviced. Over time, this documentation becomes a valuable addition to the equipment's service records.
Approved waveforms in the library also can be downloaded for comparisons with waveforms captured at the site, making it easier to solve unusual or unique problems. Service center personnel can also send calibration waveforms to the site, improving calibration time in the process.
Data logging
Oscilloscopes combined with PCs provide valuable data-logging capabilities. The scope acquires waveforms and sends them over the modem for storage and analysis by the PC. The number of waveforms acquired is limited only by the storage capacity of the PC. Data logging is useful for many purposes. For example, data logging makes it possible to perform trend or degradation analysis on a regular basis to determine the need for equipment adjustment or repair. This is an important ingredient of preventive maintenance procedures. Because a servicer is not required at the site, it is a cost-effective approach.
Remote monitoring and field service
As every service technician knows, service sites are often in less than ideal locations: on a mountaintop, at a remote receiver-transmitter site, or on an oil drilling platform in the middle of the ocean. Worse yet, they are often in hazardous locations, such as an environ mental-testing chamber or power-supply test station. In conditions like these, tele-servicing capabilities are desirable and can be critically important to the safety of the servicer.
Because the scope probes can be attached and left in place without an operator in attendance, tele-servicing is a good solution for hazardous or remote service sites. If the service problem involves intermittent failures, the scope can be set up in a babysitting mode and left to capture the critical signal when ever it occurs.
The Tektronix CAT200 is available for about $350. The Tektronix 222 digital hand-held oscilloscope is available for about $2,350. The RS-232 cable costs about $20. LabWindows and the Lab Windows Tek222 instrument driver is available from Tektronix for about $595. The LabWindows Advanced Analysis Library is also available for an addition al $895.
Also see: Servicing Zenith microcomputers: Part VI: Data and parity RAMs