Networks and Communications
ControlLogix Provides the Passport to Success for MJ Engineering
When Complete Automation leader Rockwell Automation, launched its new Allen-Bradley ControlLogix platform, MJ Engineering were quick to identify its potential. ControlLogix combines PLC, Motion and Communications into a single integrated unit, offering the ideal solution for a new machine MJ Engineering were producing.
MJ Engineering based in Tiverton, Devon, specialises in the design and manufacture of special purpose machines. One of their projects was a new machine to manufacture plastic security wallets in a range of different styles and sizes using various combinations of plastic film and paper.
The application demanded a powerful processor to maintain overall control of the machine including motion and speed control. MJ engineering was also interested in networking devices together to reduce interconnecting wiring and speed installation and commissioning. Consequently, they decided to specify DeviceNet to provide the communications throughout the machine.
DeviceNet is an open network that provides ease of integration with "plug and play" pre-configured devices. It is a bus-based system with a single network cable replacing multiple wiring. DeviceNet products are now available from over 300 independent vendors and the machine uses products from Rockwell Automation, SMC and Eurotherm. DeviceNet made it easy to connect the devices together and the diagnostics built into these 'Smart' products provide rapid and easy troubleshooting.
Melvin Vickery is a partner at MJ Engineering, "We were a little concerned about the interconnectivity of products with DeviceNet interfaces from different suppliers, however everything works perfectly. Using DeviceNet also reduced the overall cost of the machine. Products with the DeviceNet interface were a little more expensive than standard, but we were able to save a considerable amount of time on the installation, due to simplified wiring."
At the centre of the machine is the Allen-Bradley ControlLogix system. ControlLogix is modular and can be designed, built and modified to suit the application. The flexible architecture permits multiple processors, networks and I/O to be mixed on a single chassis. At the heart of ControlLogix is the ControlLogix controller, a highly functional industrial processor that provides an easy-to-use, modular, and flexible solution.
MJ Engineering specified the ControlLogix system to comprise a ControlLogix controller, four axes of motion control, a DeviceNet module for the communications. The ControlLogix controller offers highly integrated motion control by simply inserting standard motion instructions within the controller's ladder diagram. There is only one software tool to learn and one program to maintain for both motion and sequential control. The controller provides all the communication and path information needed to integrate multiple motion axes into a single cohesive system. This results in faster application development and integration, higher system performance, and much simpler start up and maintenance.
Neil Forward is electrical Engineer at MJ Engineering "We were really impressed with how easy it is to programme ControlLogix particularly with the Motion instructions. ControlLogix is based on the IEC 1131-3 specification, and the instruction set maintains the look and feel of existing Allen-Bradley PLC controllers, so there were no new programming skills to learn.
Previously, programming the PLC and the motion control system would have been two separate activities. Many of the motion programming languages are complex, and we would have to get specialist help. With ControlLogix we simply insert standard motion instructions within the controllers ladder diagram program.
Melvin Vickery continues "ControlLogix suited our application perfectly, and we decided to train our engineers on this new product by sending them on a Rockwell Automation training course. The training was well structured to provide our engineers with a basic knowledge of how the product is used. Our engineers liked the hands on sessions which allowed them to build on this knowledge with live projects in the factory."
The new machine is around 5 meters long and is based on a combination of electrical and pneumatic controls. Film is fed through the machine in a process similar to a web printing press. It uses two rolls of feed material to form the top and bottom of the pocket. Two reels of clear polyester or polyethylene may be used or the lower reel may be replaced with a backing paper. The material feeds into the machine through a system of 'dancing arms' to maintain a steady tension. A laser sensor measures the diameter of the feed reel and calculates the unreel speed to match the demand. The top film passes through a punch station and the lower film through a perforating station. Each station can punch or perforate very accurately using sensors to detect index marks on the feed material.
The two films come together at the sealing heads and here high temperature jaws weld the material both in line and across the web to form the 'pockets'. The welded material can then be either cut into sheets and fed along the conveyor to be stacked and packed, or it can be spooled onto a rewind drum. The speed of the machine depends on the complexity of the material being produced but is typically one finished item/second.
Three Allen-Bradley 0.55kW B 160C SmartSpeed controllers driving through reduction gearboxes control the feeder motors. These compact speed controllers have a simple plug-in DeviceNet interface and the speed is controlled based on the diameter of the spool and the demand rate.
Overall control of the machine is by means of an Allen-Bradley PanelView HMI located in a remote console adjacent to the conveyor. The PanelView is connected to the ControlLogix system by means of a DeviceNet link. The PanelView is menu driven and allows the operator to adjust the style and size of the pockets.
Neil Forward is enthusiastic about the new ControlLogix product, " We have to design and manufacture these machines to tight deadlines typically in the order of 20 weeks. New products that help to speed this process are very important to us and the new Allen-Bradley ControlLogix has made a significant contribution to the design and installation of the electrical control system. Having motion integrated into ControlLogix enables us to programme the unit ourselves and DeviceNet has reduced cabling costs and made commissioning quicker and easier.
The support we have enjoyed from Rockwell Automation has been first class. The telephone response is excellent and they log all the enquiries so you don't have to go over all the same ground again. We even had a visit from an application engineer to help with one part of the project.
Now we have the training and experience with the Allen-Bradley ControlLogix system we will be using it again on any project where the integrated platform will help to save us time and cost."
For further information, please contact:
Rockwell Automation Ltd
Pitfield, Kiln Farm
MILTON KEYNES, MK11 3DR
Tel: 0870 242 5000
Fax: 01908 839696
Technical: John Pritchard
Product Manager - Motion
E-mail: jpritchard@ra.rockwell.com
General: Jennie Holmes
Marketing Communications Manager
E-mail: jholmes@ra.rockwell.com
Sales Leads Rockwell Automation Response Centre
DBI
31A Chelsea Wharf
15 Lots Road
London SW10 0QJ
Tel: 0870 242 5009
E-mail: rockwell@dbi-ltd.demon.co.uk
Issued by Fisher Marketing Limited
Kingfisher House, 54 Banstead Road
CARSHALTON, Surrey, SM5 3NW
Tel: 020 8643 0240
Fax: 020 8770 9511
E-mail: fmpr@fishermarketing.co.uk
NEWS
Ref: App/00E February 2000