Pulsecom SU-X remote intelligent maintenance unit
Pulsecom model SU-X industrial communication module. This is marked "SU-X", "D105358-1" and also has a bar code stickers marked "D45D52B3AA". It has the original instructions and box. According to the instructions, this is a "SU-X Remote Intelligent Maintenance Unit". The instructions are dated 1992.
This is from the estate of an industrial telecommunications engineer and ham radio enthusiast. We don't know much about it. We have not tested it and the box is worn and dirty from storage.