2. How many meters can the serial communication line connect?
TTL communication: If the communication value is 2 meters under the 9600 TTL transmission, the actual application is recommended not to exceed 50cm. This has a relationship with the electromagnetic environment, which is mainly limited by the load capacity and anti-interference ability of the TTL device.
232 communication: RS-232-C standard stipulates that the drive is allowed to have a capacitive load of 2500pF, and the communication distance will be limited by this capacitor. For example, when using a communication cable of 150pF/m, the maximum communication distance is 15m; if the power per meter is As the capacity is reduced, the communication distance can be increased. Another reason for the short transmission distance is that RS-232 is a single-ended signal transmission, which has common ground noise and cannot suppress common mode interference. Therefore, it is generally used for [rs232 (9-pin) interface] communication within 15m.