Since using EIA-485 port standard, DMX512 prescribes that number of the equipment connected in a data bus can't exceed 32. It is determined by the electrical characteristics of the port circuit. Now some port IC has been improved on this characteristic. Using these IC in the equipment, the data bus can connect more equipment.

In the engineering application, it is impossible to check every IC characteristics of all equipment. Therefore, it is proposed to follow the maximum connecting number of the EIA-485 rules strictly.