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MAY-JUN 2018

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22 INTECH MAY/JUNE 2018 WWW.ISA.ORG an external display, a significant benefit. If the touchscreen is sufficient, then the OEM can save the expense of pur - chasing and installing an external HMI. If the vendor includes an HMI develop - ment tool as part of the EPIC software package, a low-cost graphics monitor can simply be connected to the HDMI port to provide an external HMI. In that case, there is no need for an external PC- based HMI, which is very expensive due to the high costs of industrial PCs and PC-based HMI software. Programming options Multiple programming options are re quired for any modern EPIC. Some of the more popular languages are flowcharting with scripting options for sequential machine and process skid control, and the suite of IEC 61131 lan- guages. These two options will be suffi- cient to support most real-time control needs, but some OEMs may require or prefer more flexible and powerful pro- gramming languages, such as C/C++, Python, and Java. These and other lan- guages can be most easily used if the EPIC provides secure shell access, a common feature when a Linux operat- ing system is used. And all of these lan- guages can be used together, with data passing among them internally within the EPIC as required. For many remote access applica- tions, real-time control is of second- ary importance, with data exchange among various controller, HMI, and other platforms the primary goal. For these types of tasks, the browser-based, open-source, flow programming tool Node-RED (https://nodered.org) is be - coming more widely used by EPIC ven- dors, and by many other companies in both the commercial and industrial sectors (figure 2). Using this open-source visual lan- guage, developers can cut and paste prebuilt function blocks or nodes to con- figure various communication paths. Be- cause Node-RED is specifically designed for these types of tasks, it is much easier to use for data handling than languages designed for real-time control, such as flowcharts, or general-purpose languag- es, such as C/C++, Python, or Java. Industrially hardened Many of the capabilities mentioned above are in commercial data collection products, specifically PCs with plug-in data acquisition cards. But using these products in an industrial environment presents a number of problems. First is the difficulty of mounting and protecting commercial compo - nents, such as a desktop PC, in an industrial enclosure. Second is the high likelihood of failure after instal - lation due to temperature extremes, shock and vibration, electrical noise, and other conditions common in in - dustrial environments. Third is the lack of certification for use in haz- ardous locations. To avoid these and other issues, any EPIC intended for an industrial re mote access application should meet mini- mum requirements, including: l DIN-rail mounting l operation from about –20°C to 70°C l industrial microprocessor l solid-state drive l certification for use in hazardous locations One of the most basic functions for any remote access system is connect- ing inputs to I/O terminals in an effi - cient manner. FACTORY AUTOMATION Figure 2. The open-source Node-RED programming tool embedded in edge controllers enables users to easily wire together hardware devices, APIs, and online services. Figure 3. I/O modules provide a visual indication of the overall module status, and a touch-sensitive pad activates the display of diagnostic information for each channel on the embedded HMI, simplifying startup, commissioning, and maintenance.

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