The FS9100/8.8 is submodule which has to be connected directly to FS9100/8 main output module. FS9100/8.8 connects to FS9100/8 main output module directly thru SDA-SCL dataline. SDA-SCL dataline can be up to 5m (16.4 feet). Each module uses an address and it is changable by jumper on the pcb. The FS9100/8.8 has 8 relay outputs and all outputs has status LED for quick check on installation.