L293D is a dual H-bridge motor driver integrated circuit (IC). Motor drivers act as current amplifiers since they take a low-current control signal and provide a higher-current signal. This higher current signal is used to drive the motors.
ESP8266 is a highly integrated chip designed for the needs of a new connected world. It offers a complete and self-contained Wi-Fi networking solution, allowing it to either host the application or to offload all Wi-Fi networking functions from another application processor.
All kinds with RS485 port device parameter settings , data communication
Short distance , such as parameter settings of the computer peripheral equipment , the use of common data lines can be .
A and A port of the device when the wiring is connected , B and device B connected . Some devices D + A and D, – B .