GMA-M Series encoder is a Multi-turn bus-based Modbus absolute encoder, it can provide max 16bits sing-trun resolution, with options of housing Dia.:38,50,58mm; Solid/hollow Shaft Diameter:6,8,10mm, Output Code: Binary, Gray, Gray Excess, BCD; Supply Voltage:5v,8-29v; MODBUS is a request/reply protocol and offers services specified by function codes. MODBUS function codes are elements of MODBUS request/reply PDUs. The objective of this document is to describe the function codes used within the framework of MODBUS transactions. MODBUS is an application layer messaging protocol for client/server communication between devices connected on different types of buses or networks.