Direct connection to bus; switchboard modules in IP 20 housing. Modularity (8/8, 16/16, 32/32 DIO) for digital I/Os only. Mounting on DIN rail. Modules can be networked with various bus types (INTERBUS, PROFIBUS DP, CANopen, DeviceNET, Ethernet). Suitable for smaller applications where the number of DIO can be estimated in advance. A cost-effective solution.