Taking the logical way forward

Paul Boughton

For over the past decade, logic modules have stood the test of time whether for use with simple components including time switches and contactor relays, or more advanced technology environments such as PLCs. Joanne Banks highlights some recent additional functions added to the latest generation of LOGO! logic modules - widening the fields of application considerably, as well as simplifying configuration tasks.

It is clear the gaping void between conventional switch technology and PLCs in the automation market was rectified back in the mid 1990s with the introduction of the LOGO! logic module from Siemens. It offered an efficient alternative for simple automation tasks and its secret was the novelty of its flexibility in application, together with easy configuration.

For the user this meant a combination of benefits ranging from space saving and reduced wiring requirements through the use of a programmable logic module, instead of many conventional components.  This lead the way to programming without a PC and simple commissioning and testing.

From this point, the logic module has gone on to lead the market in this performance category, developed in many areas such as increased digital outputs, larger programme memory, integrated analogue inputs, modular expandable units, reduced cycle time and external display improvements.

Other selling points have included the usability of all three power phases in one configuration, or the option to combine units for 230 V signals in domestic use.

Today’s LOGO logic module has now evolved to include a number of additional functions to support solutions for the flexible, efficient and cost-effective automation of small applications for industry and building requirements. Two additional logic modules, 12/24 RCE and 230 RCE can take advantage of the Ethernet world communication standard, opening the possibility for programming and communication via Ethernet using interfaces such as SIMATIC S7 CPUs, HMI Panels or via OPC servers and PCs.  This opens up new opportunities for data storage and graphic visualisation, online remote access to the logic module, or for operator guidance such as touch screen technology.

Standard SD cards can be used as a cost-effective external storage medium.  Programmes can be copied, as well as data and projects saved for ready availability.

The LOGO! software Soft Comfort has been continuously optimised over recent years, especially to aid configuration needs. Simplicity and flexibility objectives have been met to ensure configuration can be undertaken simply by both ladder diagram and function block diagram means.  Individual function blocks can be linked to the user programme using drag and drop, while programme tests are possible as offline simulations or as online tests.  The software also offers professional documentation and printing functions. Important new features of Version 7 of the software are the implementation of the commands for communication, the creation of user defined function blocks with a library function, the support of the data logging and the five new function blocks.

LOGO! is suited for implementing simple automation tasks in industry and building management systems. With the use of expansion modules, LOGO! can control even the most complex plants without any problems.

For more information, visit www.siemens.co.uk

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