>> “In the case of packaging machines for the food or pharmaceutical industries, in particular, the WT 18-3 information sensor opens up completely new opportunities regarding validation”, says Ludger Richter, Meurer’s Sales Manager. “Sensor adjustment is no longer described in written form but stored as a reproducible parameter set in the machine control system itself, and is called up from there when necessary via the Sensor Hub – a fieldbus connection module”, explains Walter Schmidt, the Works Manager.

Complete information to and from the sensor

The sensor owes its fieldbus capability to a chip technology specially developed for photoelectric proximity switches, and to the Sensor Hub. The new chip consists of a receiver with 16 elements with a programmable virtual separating seam for the electronic adjustment of background blanking. Not only are the scanning distance and scanning range of the WT 18-3 now more rapidly, more precisely and more application-specifically definable, but also highly reproducible. The fully electronic sensor concept is a prerequisite for two-directional communication – the Sensor Hub, to which up to four WT 18-3 units can be connected via an unshielded 4-pin standard cable, provides the physical basis. In this way the sensor can be visualised and contacted, as fieldbus participants with distinct addresses, from the machine control panel as well as from a distant control room, and the particular settings and state data called up,” says Walter Schmidt.

For intelligent and compact packaging machines

The new sensor technology allows considerable improvement in the design and operation of packaging machines. “Because remote settings can be made, and the sensors no longer need to be accessible, they can now be integrated in the machine at optimum locations for the process, despite limited space, and still be well-protected against environmental conditions,” says Ludger Richter. Whether device exchange, changes in format, or sensors employed in parallel – whatever the case, parameters are no longer set or altered manually, but are downloaded from the machine controller. Moreover, calling up status information, for example on the actual signal quality, allows any problems to be dealt with in good time during planned machine downtimes.

On the way to standard technology

Sensors with the new chip technology are well on the way to becoming the new standard in automation technology. This is not solely because of the technological aspects, but also for reasons of operational practice. On the one hand, the device is downwardly compatible, i.e. can be replaced by any conventional sensor when necessary, e.g. the WT 18-2 predecessor series – minimising machine downtimes if there is a problem. On the other hand, the entire sensor and Sensor Hub concept can be retrofitted in existing machines with a fieldbus infrastructure. Further “information sensors” are already available, e.g. for detecting small parts in the electronics industry, or objects on conveyors in transport and warehousing systems.



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