With bar code positioning systems, the read head is moved along a bar code tape. It calculates the absolute position data in the direction of travel with millimeter accuracy up to a distance of 10 km. The bar code tape is simple to use and can be bonded both in straight lines and in curves. Maximum flexibility, simple mounting, transparent diagnosis as well as a large selection of integrated interfaces are the strengths of this system. The new “availability control” function allows diagnosis to be performed during operation.