FC1: Read Coil Status
FC15: Force Multiple Coils
FC16: Preset Multiple Registers
FC2: Read Input Status
FC22: Mask Write Register
FC3: Read Holding Registers
FC4: Read Input Registers
FC43/14: Read Device Identification (TCP/RTU)
FC5: Force Single Coil
FC6: Preset Single Register
FC1: Read Coil Status