The Kuhnke 653 and 657 series PLC's are older rack style systems, developed before decentralisation of I/O. Typical units comprised many I/O cards in slots, interconnected to power supplies, watchdogs, CPU's and memory devices, all housed in a single cabinet. Larger units could have up to 1000 I/O.
Although few of these PLC's are now built, a large number continue to operate in the field. Most replacement cards, with part numbers such as 657.440.02 are easily available.
The product information and datasheets shown on these pages are for obsolete products and should be used only as an aid in re-design or re-engineering.