Klinikum Fulda is a hospital that provides medical care for more than 500,000 people in eastern Hesse. Since it began operating in its current form, it has had an automatic goods transport system (AWT) that controls up to 360 transport containers on 700 meters of horizontal routes and 210 meters of vertical routes underground and away from the flow of patients. These supply the wards with food, drinks, medicines, medical equipment and sterile goods around the clock and dispose of waste.

After more than 30 years, there were hardly any spare parts for the system and support from the manufacturer was also problematic. In addition, the existing system could not be extended to accommodate the new clinic buildings that had been built in the meantime. The spare parts situation particularly affected the control technology and the read/write system, with which the transport containers were coded and recognized at route decision points and loading points.

Magnetic strips on the bottom of each transport container served as data carriers, containing all the necessary information such as container type and origin/destination. The magnetic strips are now difficult to obtain and time-consuming to replace. In addition, the data set that can be stored on them is very limited for today's data processing. An important aspect of the modernization was that the basic functionality of the system should remain as unchanged as possible in order to keep the training requirements for the hospital staff as low as possible. And as a result of many years of operating experience, a number of errors in the old system were also to be rectified and various aspects of daily operation changed.

RFID replaces solenoid coils

After analyzing the existing system, the Heitec specialists decided to replace the outdated Simatic S5-135U controllers with controllers from the Simatic S7 family and network them with Profinet. The read/write technology with solenoid coils was replaced by a modern and expandable RFID system. The existing sensor/actuator hardware was retained at the customer's request, but integrated into the system via ET200SP input/output modules. The function of the control system is now performed by a computer with WinCC visualization software, whose visual representation of the system was largely adapted to the masks of the previously installed Intouch system and thus has a high recognition value for the users.

The required expansion of the data records was achieved by changing the concept. Only the serial number is now stored on the data carriers of each transport container; the corresponding data record is located in the control system. As the goods transport system consists of 15 different areas, it was and is being modernized in various stages. By operating the old and new systems in parallel during the conversion phases, Heitec ensures a high level of system availability. To this end, the transport containers were equipped with an RFID transponder in addition to the existing magnetic strips. In this way, they are easily identified and managed by the old and new system components. as