The D2-260 and D2-250-1 support local expansion. The D2-260 supports local expansion up to five total bases (one CPU plus four expansion bases) and the D2-250-1 supports local expansion up to three total bases (one CPU bases plus two expansion bases).
A D2-CM Expansion Base Controller Module is placed in the CPU slot (far left slot) of each expansion base. The D2-EM Base Expansion Module is attached to the right side of each base in the expansion system. The category 5 straight-through cable D2-EXCBL-1 is used to connect the expansion modules together.