The EXP1x adds eight RAD ports to a HAL1x via the Expansion Bus. The EXP1x requires a HAL1x to operate. DR remotes are also supported on any RAD port, so the EXP1x also adds additional DR remotes. The graphic below shows most of the range of RADs and DRs that connect with shielded CAT 5e cable (or better). 512 inputs and 512 outputs are possible if 32 EXP1x Expanders are cascaded to a HAL1x.