By Ian Verhappen
By Ian Verhappen
Are ERP, CAD/CAM and PLM really more than just acronyms in your facility? Yes, as the articles in this issue indicate, there are facilities that make effective use of these software tools; however, many manufacturers fail to go to the next level – the sensor level, where the process is actually controlled.
The vast majority of analog transmitters installed today are HART-enabled, meaning that they are able to provide device status and diagnostic information to the network. Most process control systems support HART communications directly, and pretty much the rest of the analog signals connected today support some form of bus technology.
If your control system’s I/O cards do not have a native HART modem to communicate directly with the field devices, wired "HART strippers" are available to use RS-485 or another network to bring the diagnostic information back to a central location to make full use of the data. Most HART devices on the market today support HART 5. However, HART 7 was released in 2008 by the HART Communications Foundation. Most people believe that the addition of wireless is the most important part of this latest version. I beg to disagree. I think the most significant addition is the "report by exception" feature. This means that you no longer have to send a command from the host to the device on a regular basis to find out if something is wrong. With "report by exception," the device can now send a message to the host to tell you if there are any issues.
HART 7 devices are just being released to market. But as existing HART devices get replaced through regular maintenance practices, this new "report by exception" capability will have a huge impact on the way we work. Unfortunately, a large percentage of installations do not effectively use the diagnostic information available in their devices today, because they are not collecting the information in a central location. The most common tool for the centralized collection of sensor-level network information is asset management software. Unfortunately, most providers of this software make the software too complete, so that the tool can, in addition to collecting, analysing and interpreting the data, also generate work orders, thus duplicating the efforts of the corporate ERP software. Of course, you can turn this off and integrate the asset management software with your ERP system. A series of standards are being started to provide some guidelines on how this should be done. The ISO body is in the process of adopting British Standards Institution’s publicly available specification, PAS 55 – Optimal management of physical assets, as the starting point for a new series of documents. If you have an interest in this area and want to help, please contact me. Unfortunately, the ISO/BSI work is focused on asset management at the financial or highest ERP level, and though it may provide general guidelines, it will still need work to be applicable at the control and sensor level. A number of interested individuals are considering forming a committee within the ISA standards department to develop the requirements for asset management at the field level, so if you are interested, please contact me.
Ian Verhappen, P.Eng., is an ISA Fellow and ISA Certified Automation Professional. He operates Industrial Automation Networks Inc., specializing in field-level industrial communications, process analytics and heavy oil / oil sands automation. He can be reached at email@example.com.