Product category:
Smaller-Sized PLCs
News Release from: Siemens Automation and Drives | Subject: Simatic S7-200 Micro PLCs
Edited by the Engineeringtalk Editorial
Team on 30 May 2005
Micro PLC is put to the Sword
Sword Electrical specifies Simatic S7-200 Micro PLCs on its contracts for the industrial extraction industry.
Sword Electrical is a young business of four employees that is starting to make a name for itself in the north of England According to cofounder Paul Ward, part of the company's immediate success is due in part to its specification of Simatic S7-200 Micro PLCs from Siemens, a product used extensively on its contracts for the industrial extraction industry
"Our main business as a system integrator and contractor is to construct control panels for industrial extraction systems", explains Ward.
"Our panels frequently end up in places like saw mills and kitchen factories; anywhere that is likely to create a lot of dust as a result of its manufacturing processes".
To control the hard working motors and large extractor fans specified for many such projects, Bradford-based Sword Electrical selects Simatic S7-200 Micro PLCs.
"We've used Siemens since we started".
"My father had a business for 20 years before this one and he always preferred Siemens, and I'm the same".
"For me, the main reason is the Step 7-Micro/WIN software".
"There may be cheaper PLCs on the market but for ease of programming the S7-200 software is second to none".
"Its toolbox concept accelerates program generation".
"Our customers really like it too as its modular design means it's open-ended enough to be expanded at anytime in the future".
However, not all installations are straightforward, as Sword recently discovered at Gower Furniture, a manufacturer of MDF furniture.
Gower has enjoyed plenty of success in its industry, which has allowed the company to grow and invest heavily in automating its factory.
However, with the increase in business has come an increase in the amount of airborne MDF dust, which can be harmful if inhaled.
It became apparent that Gower's factory's dust extraction system had to be upgraded to meet the requirements of the health and safety factory inspectors.
Gower uses two 110kW fans that extract the dust through a series of ducts into silos, from where it is subsequently collected by the local water authority and used in sewage treatment.
To maintain the suction at full power it is necessary to clean the filters in the dust collection chamber by forcing compressed air through each filter element in reverse.
The unit that cleans the filter elements is mounted on rails inside the main suction chamber.
The unit moves along the track stopping above each set of elements to execute the cleaning process before moving to the next set.
Sword approached Siemens to see if the company had experience using slip rings for PPI (RS485) communications.
The intension was to supply power and communications to the control panel on the filter element cleaning unit via slip rings.
However, the cost of slip rings for the communications was proving to be expensive and had potential reliability problems.
As an alternative, the solution offered by Siemens was to provide communications between the S7-200 PLC in the main control panel in the factory and the filter element cleaning control panels in the main suction chamber using wireless Ethernet communication units, hence overcoming all potential cost and reliability problems associated with slip rings.
"In this particular application networking the two PLCs was proving particularly problematic", confirms Ward.
"So when Siemens came up with a wireless solution using their new Ethernet expansion modules connected via D-link wireless access points, it really saved the day".
"The product and the support behind it means that we will be specifying Simatic S7-200 Micro PLCs for the foreseeable future".
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