CP-RIO3-04 Rear I/O module for CP305, CP307, CP308, CP3002 and CP3003 The CP-RIO3-04 is the Rear Transition Module for the CP305, CP307, CP308, CP3002 and the CP3003 3U Compact PCI CPU boards. This Module can be used to access the I/O's from the back of the system. The CP-RIO3-04 is available as single slot (4HP) or dual slot (8HP).