The system modules for the CX2000 family are connected to the CPU on the left-hand side via a multi-pin connector. Internally they are connected via PCI Express. Up to four modules can be connected in any order. The CX2500-0020 audio module has jack plug (5 x 3.5 mm) and cinch plug for digital signals (SPDIF). Up to 7.1 multi-channel audio can be used. Serial interfaces can be added with the modules CX2500-0030 (RS232) and CX2500-0040 (RS422/RS485). The CX2500-0060 module provides two further independent Gbit Ethernet interfaces. The CX2500-0070 module can be used to add up to four further USB 2.0 interfaces.