Industrial application of Profisafe

Many machines are built with fail safe design that intends to protect operators and people working near them from danger. Manufacturers of all fields usually dislike having unscheduled downtime, unexpected machine stoppage resulting from equipment failure, operator error or nuisance trips as well as having their human capital affected by hazards at the workplace. Safety solutions available today such as Profisafe integrate directly into standard control architectures, helping to curtail downtime by allowing operators to diagnose machine stoppages more intelligently and determine nuisance trips and alarms and at the quickly get production up and running again

Protection in Manufacturing Cells

In the industry the Profisafe can be applied to protect foreign object such as human hand to enter a manufacturing cell. The Profisafe technology is incorporated into drives

Figure: Entry and Exit of a Manufacturing Cell

Figure: Motor Configuration With Safety Function

That is combined with laser scanners and light curtain. The laser scanner with its field only allows parts with a well defined shape and contour to enter the manufacturing cell. It is a presence sensing device [1] The area of coverage of the protection field can be programmed into the system. In a light curtain based conveyor system muting sensor are used to deactivate the light curtain when there is a object passing [4] . This is one of the cases where it is possible to make use of the drives with integrated safety functions [3]. The safely available position of the motor can be used for the necessary changeover of the protection fields instead of the muting sensors [3]. This is cost saving as the amount of hardware as well as hard wiring can be reduced and the muting sensor is not necessary as the safety function are taken over by the Profisafe network. This causes the system to be more robust and thus a higher availability can be expected. This function is sometimes called a safety software switch[3]. They can also be used in limit switches in applications with linear movements. However, additional hardware switches are still mounted normally for safety reasons[3]. These hardware switches can removed when a drive has integrated safety as the likelihood of a failure can be disregarded.[3]. Besides taking over the functionality of the muting sensor, The laser scanner in a manufacturing cell together with the profisafe network can be used to demonstrate another cost saving application. The laser fitted to many hazardous manufacturing cells usually has a warning field that is larger than the protection field[3]. This allow anybody who is approaching the cell to be given a graphical or alarm to be warned not to enter the manufacturing cells dangerous area [3]. If anybody comes very close to the manufacturing cell the manufacturing cell production speed can also be lowered as to prevent a abrupt sudden stop and to allow a short time frame should the person accidentally enters the dangerous zone[3]. This is best suited if the manufacturing cell is carrying out welding or gluing that has to be slowed in order to be stopped[3].

Application of Profisafe in Gantry Robot

A gantry robot consists of a manipulator mounted onto an overhead system that allows movement across a horizontal plane[5]. An American company CAMotion pioneered Safety over Wireless in a Gantry robot. Gantry robots are used in a wide variety of materials handling applications in many industries. Ussually gantry robots are equipped with vision and sensor with dynamic movements to carry out its. The competition is keen for sophisticated machines that end-users perceive as giving them a competitive advantage. CAMotion, Inc., a Robotic OEM and integrator based in Atlanta in the USA, recently developed a vision-guided overhead gantry robot for a Fortune 500 manufacturer. The system is equipped with a host of sensors to identify the shape, size and type of parts to be moved as well as to verify starting and destination locations. The automation solution includes patented motion control software that dampens oscillations caused by the movement of the gantry over Zimmerman rails[2].

CAMotion User Profinet Over Wireless To Transmit Both Safety-Relatedand Normal Control Data Between The Overhead Gantry And The Main

Control Cabinet

As with any machine with moving parts, the gantry is also outfitted with safety devices ranging from light curtains to laser scanners to protect personnel working on or near the machine. In addition, CAMotion was interested in using a wireless solution to cut down on cabling costs and to eliminate the physically complex cable solutions that are commonly used. While “normal” automation components could have tackled this job, the company sought a forward-looking solution that would take advantage of recent developments in both networking and safety technology. According to CAMotion’s engineers, the only solution available on the market that offered both wireless connectivity and distributed safety was a combination of a Siemens failsafe PLC networked to safety devices via Profinet using the PROFIsafe protocol. The Siemens S7-315F control eliminated the need for a separate safety PLC or safety monitor by combining normal and safety functionality in a single CPU. That alone reduced the upfront hardware costs of the machine, but will also likely lower lifecycle costs for the end-user by simplifying maintenance in the long run and shortening downtime. The availability of products to transmit Profinet wirelessly fulfilled CAMotion’s desire to reduce cabling costs by as much as 30 percent as well as to shorten installation time and simplify start-up. The benefit of using a single bus was the fact that both normal and safety devices could be combined on just one network[2].

CAMotion’s system architecture now uses Profinet between all devices, regardless of whether they transmit safety-related or normal data. To bridge the gap between the PLC in the stationary cabinet and the industrial PC in the moving gantry, Scalance wireless access points from Siemens are employed to transmit data seamlessly on Profinet. CAMotion’s vision was to have both standard and safety-related data transmitted wirelessly to support future expandability and rapid deployment. CAMotion feels the use of the combination of asingle failsafe PLC together with a single bus for both standard and safety-related data hasgiven it a distinct competitive advantage in both price and performance that has resulted in lucrative, long-term business[2].

The Use of Profisafe in Automobile Company

Automobile manufacturers typically lead the rest of the industry in the adoption of new technologies. Carmakers and their suppliers are highly engineering-driven and work closely with automation suppliers in specifying and testing new solutions. As with the AIDA group of carmakers mentioned previously, this includes integrating safety into automation systems

to help lower both start-up and operational costs[2]. One company with a reputation for innovation in the Scandinavian automobile industry is Rejlers, a systems integrator based in Sweden. The local office in Skovde recently designed the architecture for a new handling linefor pistons and connecting rods around failsafe PLCs from Siemens networked to safety devices and standard I/O via Profinet and PROFIsafe. The line consists of several machines that mark, classify, sort, buffer and palletize up to 60 different piston types as they come out of production. Parts handling is now fully automated using robots from ABB to identifyparts and store them in temporary buffers. The previous solution consisted of standalone machines with only semi-automated handling. The new automated solution employs uses Profinet as a backbone medium to network safety PLCs, industrial PCs and standard I/O blocks as well as emergency stops, light curtains, and safety interlocks. According to Rejlers, engineers decided on the PROFIsafe/Profinet solution despite slightly higher hardware costs because of the lower time it takes to install and integrate the system components. The company estimates a 30 to 35 percent time savings in integration efforts by using this architecture, thanks mostly to the solution’s flexibility. A Rejlers engineer stated, The hardware configuration is usually not finalized at the beginning of a project. Using Profinet, we can easily ‘integrate in’ an additional safety component on short notice - something that would take a lot more time with a hard-wired solution”. Due to the success of the initial project, the integrator has already been awarded follow-on contracts to extend the line in the near future[2].

Rejlers’ Architecture Uses PROFINET To Network Both Standard I/OAnd Safety Devices

References:1.Retrieved from Wiki: http://en.wikipedia.org/wiki/Light_curtain.

2.ARC Advisory Group (n.d.) PROFIsafe: Networked Safety for Processand Factory Automation. Retrieved April 4, 2011, From http://www.automationworld.com/whitepapers/arc-wp-profisafe.pdf3. Wolfgang Stripf (2006, November). Safe. IET Computer and Control Engineering. Retrieved April 4,2011 From http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4114387

http://www.ab.com/en/epub/catalogs/3377539/5866177/3377569/6388297/2875466/3379607/tab4.html

4.Schmersal Inc(n.d) Muting Safety Light Curtains: Applications & Use Retrieved April 4,2011, From http://www.schmersalusa.com/catalog_pdfs/MutingSafetyLightCurtains.pdf

5.Robot Word (n.d) Gantry Robot Retrieved April 4,2011, From http://www.robots.com/faq.php?question=gantry+robot