Modbus Function	Valid Range	Description
(0x02) Read Discrete Inputs	0 - 15	Reads the opto-isolated inputs.
(0x01) Read Coils	0 - 7	Reads the state of form C outputs.
(0x05) Write Single Coil	0 - 7	Writes to a single form C output.
(0x0F) Write Multiple Coils	0 - 7	Writes multiple form C outputs.