The HX is the C200H Alpha. These PLCs are still manufactured and supported. How about the "V" number of the CPU and the rack? This could be important. You should be able to purchase an expansion rack, power supply, cable etc on EBay or PLC Centre. Have to go out to a job - will look up and post the part numbers when I get back late this afternoon. Just post the full parts numbers for me. The processor will be something like C200HX-CPU44-E and possibly a V number. The rack number will be something like C200HW-BC081-V1. The V number may be important - I have not used one of these for probably 5-6 years - use the CS1/CJ1/CP1L series now.
Do you have cables, software and interface modules to allow you to program the PLC? If so post the part numbers of what you have. If not I will post what you need on my return.