Automation & Control
convenient control solutions they can customise to suit specific application needs. With this new line, we are delivering the functionality and flexibility of a micro PLC for the price of a smart relay. The greatest value of the new Micro800 family is the simplicity and convenience it offers users - namely, that it provides ‘just enough control’; users will only pay for what they need.”
Multi-purpose screen
An example of this approach can be seen on the front face of the Micro810, the smallest product in the family. A removable screen - which also doubles as a program storage and transfer medium - is an option as opposed to a standard feature (Fig. 2). Customers can therefore opt for a lower-cost unit without a screen and program the unit via other means, or purchase multiple screenless units and one screen that can be moved from controller to controller as required for either programming or maintenance. This option, Rockwell Automation believes, is not available anywhere else at this price point. Pethick continues: “By offering multiple plug-in modules,
developed by us and our Encompass Partners - all of which are common across the line - we can help machine builders ‘change the personality’ of the base unit controller in order to address a multitude of different bespoke scenarios and machine sizes. Indeed, to borrow a well- worn phrase, we can now say ‘there is a plug-in for that’.” A clever design feature
is that the plug-in modules house their own terminals, so installing additional modules does not consume valuable input/output (I/O) terminals on the base unit. Furthermore, the modules mount on the front of the base unit, not the side, so the controller footprint remains unchanged (apart from the
Fig. 2. The Allen-Bradley Micro810 smart relay has an optional removable screen that doubles as a program storage and transfer medium.
expansion I/O modules for the Micro850, which mount on the side). For programming the
Micro800 family, Rockwell Automation has created Connected Components
Workbench, a free component-class programming and configuration environment that combines all primary application development needs into a single package. Through this software and ‘building block’-style application packages, customers get an estimated 80 per cent of their required infrastructure, with the remaining 20 per cent being application-specific. As might be expected today, the Connected Components
Workbench follows established IEC-61131 standards, supporting ladder diagram, function block diagram and structured text programming. It also enables machine builders
to configure other devices in the system, including Powerflex drives and Panelview Component human-machine interface (HMI) products. The software comes in two versions: Standard, which can be downloaded for free; and Developer, which benefits from additional functions, an offline controller simulation and advanced debugging capabilities. As the smallest of the Micro800 family, the Micro810
programmable logic controller features embedded smart relay function blocks that can be configured via a USB port or the optional removable 1.5-inch LCD and keypad. The function blocks include Delay OFF/ON Timer, Time of Day, Time of Week and Time of Year. Outputs are rated at 8A to eliminate the need for external relays, and DC models allow four inputs to accept 0-10V analogue signals. Slightly larger versions of the Micro810 have more
memory and digital I/O capability and either one or two slots for adding analogue I/O, a temperature sensor, a serial port and other plug-in modules.
Multi-axis motion
For customers needing more complex functionality, the Micro830 manages up to three axes of motion. It can also accept a maximum of five plug-in modules and it benefits from enhanced communication options. The Micro 850, the largest unit in the range, will be
available at a later date and will offer embedded Ethernet/ IP communications for interfacing to PCs, Panelview Component HMIs, Kinetix drives and Powerflex drives. This controller will have the same form factor as the larger models of Micro830, but will also be able to support up to four expansion I/O modules. Of the existing smart relays on the market, one of the
most sophisticated is the Zelio Logic family manufactured by Schneider Electric. These units, previously marketed under Schneider’s Telemecanique brand, are available in numerous different variants, with relatively large displays and memories, which gives them a distinctive advantage in some applications. Customers also have a wide choice of accessories and add-
on modules, which is one of the benefits of a product line that has evolved over a relatively long period. However, one of the shortcomings of this product line
has been that the Zelio Soft programming software was not compatible with Windows Vista or Windows 7. This changed in December 2010 when Zelio Soft 2 V4.4 was released, which is compatible with these newer operating systems and also Windows XP, which is still commonly encountered in industry, even though Microsoft is withdrawing support for this superseded operating system. As mentioned earlier, there are many suppliers of smart
relays in addition to those mentioned above. In some cases the units are referred to as micro PLCs or nano PLCs, and there are also compact board-based PLCs and ‘on-chip’ PLCs that can be embedded within products. Over the last decade smart relays have evolved, and new add-ons and accessories have been introduced but the Micro800 from Rockwell Automation is possibly the most exciting development. However, we will have to wait and see if this is the first
of many new product launches from automation suppliers all keen to maintain their share of this very competitive market. l
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