What protocol should connectors for fan coil control of central air conditioning in buildings be compatible with?

Q: What protocol should connectors for fan coil control of central air conditioning in buildings be compatible with?

A: Compatibility with the Modbus protocol (a common protocol for building automation) is required. The simple DIN connector (4Pin) is recommended, which supports 0~10V analog signals (for controlling fan speed and valve opening) or RS485 digital signals (for transmitting temperature and wind speed data) with a transmission distance of ≤1000 meters (covering 100-story buildings). It has an IP65 protection rating to prevent condensation from fan coils, and a tool-free threaded locking design that can be fixed by rotation, facilitating quick replacement by building maintenance staff.