23 October 2008
Business IT systems are hungry for data from the factory floor—the right kind of data, that is. In the manufacturing process, RFID tags can end up storing a lot of it, and so they become natural repositories of sought-after data.
Siemens is one control and automation provider who has been working with RFID for over 20 years, long before IT and most of the rest of the world even knew what it was. Today Siemens is clearly the leader of this technology field, but other manufacturers such as Turck have joined them as component suppliers. Other sensor providers, ifm, Sick, and Pepperl+Fuchs, have become players in the field.
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Photo caption:
Simatic RF-Manager now links RFID with automation data from Simatic S7 controllers and also collects data from mobile handheld terminals.
Siemens’ latest announcement is a upgrade to its Simatic RF-Manager software, which can now be used to link RFID data with automation data from Simatic S7 controllers. The software selects and transfer some of these data into business systems.
On the factory floor, this means more complete integration of the programmable controller (PLC) system with RFID data. Control tasks, for example, can be triggered by some data read by an RFID reader; for instance the PLC could set a switch depending on the position of an RFID tag. Going in the reverse direction, read or write tasks for an RFID reader could be initiated by a signal from the PLC. RFID data which has already been read can be transmitted to the control system, and perhaps passed on to the business system.
The software is suitable for the most diverse scenarios in logistics and distribution, from the labelling of individual products to the automatic recording of entire commodity flows. It manages readers, collects the tag data produced by the readers, compresses the data, and makes them available in the business management system with the required accuracy and quantity.
RFID ANTENNAE
Of course the first step in the RFID procedure is reading the data out of the RFID tag and into the system. The tags come in a number of different sizes and shapes with different reading ranges. Not only that, they may be placed in a variety of positions on the manufactured items and cartons, so RFID equipment makers have been creative in their ideas for pick up systems for these devices. Reading the tags on the factory floor is a task that has fallen on the shoulders of industrial controller and sensor manufacturers, who have already designed, and have a great deal of experience, of making things work in not-so-friendly or even hostile environments.
Most unusual is Turck’s new read/write head with a sensing range of 500mm, a large distance for industrial applications. The head combines antenna and electronics in one device which makes it especially resistant to interfering radiation.
The compact and flat IP67 housing (350 x 350 x 25 mm) is ideal for large overtravel ranges or where large read/write distances are required. A good example for application would be where data needs to be read out from a tag that is attached on the bottom side of a vehicle.
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Optimised for the application: Turck's roller conveyor read-write head masters bulk reading (two tags at the same time) and can be fitted easily between the rollers.
Turck has followed up the 350 mm head with another intelligent model for roller conveyor applications. This new head fits exactly in the space between the rollers of an 80 cm wide standard roller conveyor, thus ensuring reliable detection of the entire conveyor width. A special feature of the new head: Like the larger model, it also manages so-called ‘bulk reading’; that is they are capable of detecting several tags simultaneously. This is no doubt a good idea, if you’re going to have the reader that far away from the tag.
RFID AND AS-I
ifm electronic brings the good old AS-i bus into the picture with its DTA300 series of RFID readers. The system allows a user to either simply add RFID to an existing AS-i network, or create an RFID system with 31 read/write (or just read) heads. Simplicity is a benefit of this flexible system, further improved with the new heads that can read tags at distances up to 100 mm.
When the tags come into the detection range of the read/write heads the information is read at up to 0.5 m/s. The data transfer is controlled by the AS-i control level (master, controller, gateway, host). The read/ write heads are used in the AS-i network as analogue slaves with a master controlling up to 31 slaves. The compact read/write head includes, in addition to the antenna, the complete evaluation and the interface to AS-i, so that the units can be directly operated in the AS-interface network and so that the transmission of data to the controller is possible.
THE EPCGLOBAL STANDARD
The EPCglobal (Electronic Product Code) standard uses identification per RFID in the UHF (Ultra High Frequency) range; many RFID vendors including Siemens support this new standard. Using UHF allows much greater distances between the read/write heads and the transponder, making it a more useful system for supply chain logistics—in production plants, on stationary conveyor systems, or in picking areas and distribution centres.
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ifm electronic’s new DTA300 series introduces RFID read/writer head as AS-i bus modules.
To conform with this standard, Sick has introduced the RFI641 Radio Frequency Interrogator (photo, right) which can connect with up to four antennae (left). Its long range, 6m, and rapid data transfer allow companies to set up reading locations either alongside the material flow, in a gate structure above the conveyor system, or directly in a reading gate.
A number of passive transponders can be read simultaneously thanks to the multi-ident and anti-collision features.
HANDHELD READERS
They look like bar code readers, but they’re really handheld RFID readers. And they’re a lot faster than their bar code cousins, with response times significantly below 0.1sec. Thus, the read out results are almost immediately accessible to the user.
Handheld RFID readers are used mainly for maintenance and service applications. On closer inspection, they are really made to look like something else: Turck’s is built on a PDA platform, while Pepper+Fuch’s model looks like a mobile telephone stuck on the end of a handle. Siemens’ more conventional looking RF610M mobile handheld RFID terminal looks like, not surprisingly, a handheld computer with an obvious big lump on one end that houses the RFID read/write head.
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