Paper chart recorders have been the only effective method of recording process data for years. Since this was the most reliable method for collecting data, multiple processes were instituted and many inconveniences were put up with to collect, monitor and store this data. During a process run, an operator would need to make periodic trips to the process to verify the operation of the recorder. The chart would need to be checked to ensure that there was enough paper to finish the batch or that it had not jammed. The recorder pens and ribbon were checked to verify there was plenty of ink. If the ink ran out or the paper jammed during a critical batch run, the work could have to be re-run or scrapped. These rounds by the operator were absolutely necessary to ensure the integrity of the batch. In the data collection process, an operator would make trips to the process and bring back the chart paper with the process results. A location is now needed to store the chart paper. If the company’s operation is large, this archive could become quite significant over time. If a particular chart is needed for an audit, searching the archive could be a painful process. In addition to these inconveniences, there are the ongoing costs of replacing chart paper and pens and ribbon. We are all familiar with these facts.
A digital recorder replaces the paper with a color LCD display (Fig. 1). This display can be configured to imitate traditional strip charts or circular charts or can display the data in custom formats. This could include a numerical display, bar graphs, logarithmic displays, on-off data, annunciator-type display or a variety of custom displays. The point is the user can configure the display to suit their needs. Periodic rounds are no longer necessary as the process can be monitored from a central location via a network connection. No pen, paper or ribbons to worry about. Trouble with the process can be reported to the operator via e-mail or on his text-based phone. Recorder data or batch files can be easily stored to a memory card in the recorder or to a data server somewhere on the network. These archive files take up virtually no space and can be kept for years without degradation. Finding a particular batch record is as simple as a search on the archive drive. Clearly, this is the desired method to collect data.
What to Look for When Buying a New Paperless RecorderWe have found that there is a reluctance to purchase a digital recorder because it appears to be complicated. Many of the paperless recorders on the market are similar in size and accuracies. Their capabilities and functionality are similar also. There are some key things to look at before you buy to ensure you get the best product to meet your current and future needs.
Firmware UpgradesDigital recorders have the distinct ability – over paper recorders – to be upgraded in the field. As manufacturers add features and capabilities to the recorders to meet new customer demands or requirements mandated by regulatory agencies, the digital recorders can meet the new regulations with a simple firmware upgrade. Also, custom firmware for unique applications can be installed the same way. This is much better than having a salesman telling you a new recorder is necessary. Options should be easily added to the recorder when new functionality is needed.
Secure DataElectronic data and electronic record keeping are the paramount reasons for buying a digital recorder. Currently, paper recorders can give you digital data printed on the charts, but the chart still has to be kept and archived. Some paper recorders also have a network interface where data can be electronically logged from the paper recorder. This still falls short of the benefits a true paperless recorder can give you. Security of your data is the major reason for electronic records. Data collected by the recorder needs to be stored in an encrypted format and must be unalterable to ensure the integrity of the batch. If greater security is necessary, a recorder with login capability should be purchased. This should allow for unique user logins with password management, an audit trail to log user activity such as who, what and when, and electronic signatures for managers signing off on batch records.
Good SoftwareSoftware is the key to any networked recorder. The new recorder needs to have the capability of working with both the manufacturer’s software packages as well as third-party software. A manufacturer should offer software packages that will allow you to do many of the listed things.
- A package that will allow the configuration of the recorder from a PC. This configuration file should be easily saved for later use.
- A viewer package that will allow a user to view the recorder’s secure record files.
- A remote-control package that will allow users to install new configurations to the recorders, enter batch data and manage data files from a remote location.
- A logging package that will allow data from multiple recorders to be collected in a single package. This logging package allows management to see the entire operation at a glance and allows them to create reports from the data collected. A remote logging package is a plus as it allows management who may not be in the proximity of the shop to access data being collected by the logging package.
Communications CapabilitiesCommunications is where digital recorders shine. Do not buy a recorder without networkable Ethernet communications. It is over this Ethernet port where all of the advanced features will operate. A web server with a domain name gives you the ability to allow your customers to view batches as they are being run. Give it a try – go to: http://cx2000.us.yokogawa.com/. The FTP feature gives a strong ability to archive data and batch files created by the recorder. The files can automatically be transferred to a file server somewhere on the network. Typically, a secondary server can be specified if the primary server goes down. The SMTP or e-mail server gives a user the ability to have the recorder contact the user if an event occurs or if it can give periodic updates of the process condition rather than having an operator doing rounds. This data can be sent to an e-mail account or a text-based phone.
Serial communications offers another facet to the recorder. The serial comms allows software to also communicate to the unit, but more importantly it allows the recorder to collect data from external devices that are using a serial protocol such as Modbus RTU. For example, temperature controllers from your furnaces can be wired into the serial communications port of the recorder. The recorder can now collect data directly from the controller and save it. Not just information such as PV or set point can be gathered, but data such as process events and total gas or air added to the process. Once in the recorder, this data can be part of a calculation that determines, for example, total BTUs used. This is a great way for management to manage energy usage. If you need to replace controllers as well as an old paper recorder, we manufacture a unit that incorporates recording and control in one box.
Yokogawa designs and manufactures recorder and data-acquisition systems. Since releasing the ER1 in 1951, they have continued to make successive technical breakthroughs. These include the world’s first recorder with an onboard microprocessor, the non-contact ultrasonic position converter with semi-permanent operational life and high breakdown voltage solid-state relay. In response to the rapid spread of personal computers in industry, in 1995 we released a revolutionary data-acquisition system – DARWIN and the View Recorder VR100 – that are paperless and fully PC-compatible.
The DAQSTATION (Fig. 3) is currently Yokogawa’s flagship paperless recorder product that takes advantage of rapidly changing networking and Internet technology. Network functionality is what differentiates the DAQSTATION from conventional recorders. IH
For more information: Clayton Wilson, Yokogawa Corporation of America, 2 Dart Rd., Newnan, GA 30265; tel: 678-423-2524; fax: 770-251-6427; e-mail: firstname.lastname@example.org
Additional related information may be found by searching for these (and other) key words/terms via BNP Media SEARCH at www.industrialheating.com: strip charts, recorder, controller, data logger