DATA RECORDERS are available to satisfy nearly any application asked of an industrial machine builder. Trending and recording process data with a paper chart recorder is a tried and true method. It's an excellent choice when a simple paper record is needed with minimal operator involvement. Strip chart recorders are well-suited for recording continuous processes, and are commonly used in both laboratory and process-measurement applications, such as process ovens and plastics processing equipment,” explains Shahin Baghai, product development manager, Omega Engineering.
Food processing equipment and other batch processing machines that operate within a known timeframe also are well suited for circular chart recorders. They can be configured so that each rotation of the chart covers a standard time period—one hour, 24 hours, seven days, etc. Some recorders also will accommodate non-standard periods.
For monitoring and archiving large amounts of information, with quick access to historical data and PC connectivity to the process, a paperless recorder is an appropriate choice.
“Since the mission of a paperless recorder is to capture process data and display it in a meaningful manner, and then save that data to an electronic record that can be taken to the PC environment, chart recorders simply can’t compete,” says Steve Byrom, product manager, network solutions, Industrial Automation Div., Yokogawa Corp. of America.
For machine builders, even a basic videographic recorder offers several advantages over chart recorders. “Videographic recorders let users save a configuration and upload it to multiple units, gain remote access to the unit over an Ethernet connection, and eliminate most, if not all, of the moving parts from the recording device,” says Christopher King, data management product manager, Eurotherm. With vendor-supplied software, a PC provides reporting and data-retrieval functions not possible with paper recorders. Recording process variables from injection molding machines can yield data trends that help optimize parameters and improve quality of the parts being produced.
Paperless recorders can serve double duty as a diagnostic tool to monitor key data on the system, allowing the owner or service personnel remote access for viewing and alarming. “When equipped with a serial interface using Modbus protocol, the paperless recorder can acquire digital data from other devices such as a PLC, thus extending all of the inherent benefits of the recorder to the other platform,” adds Byrom. “This has proven useful to many customers who need to include low-cost recording and monitoring functions on systems and do not want the complexity and cost of a Windows-based software solution.”
The higher-level videographic recorders can handle complex applications and can be quite simple to use. Large, bright color displays that include touchscreens can be used to display recorder data, or as an HMI when used in conjunction with other instrumentation. An industrial OEM can develop custom screens for its industry-specific applications. In semiconductor wafer processing, data security is a prime concern, and videographic recorders encrypt data to make it tamperproof.
Electronic Record is the term to describe a PC data file that is considered the equivalent of a paper chart or report. Many industry monitoring and enforcement agencies have adopted regulations that establish criteria by which electronic records and signatures are the acceptable equivalent of their paper and handwritten counterparts. Industry users and agencies realized that electronic recording systems provide more accurate data, better security, and the ability to save pertinent batch information in a single, secure data file that can be archived forever and instantly recalled on-demand for review. The digital data usually can be stored locally on a disk or card, either of which can be removed for downloading to a PC. An engineer can then bring up any of the stored information for review and analysis, zooming in, for instance, on the time of a process upset.
“By monitoring parameters over time, machine builders can determine whether process improvements are indicated,” adds Baghai. “For example, the charted graphs could provide insight into the correlation between temperature and the wear and tear of an engine, or to monitor the AC current of a machine versus the temperature build-up in a component of the same machine. The charted graphs would show how the two parameters correlate, perhaps indicating that the component’s temperature rise will lead to premature failure.”