Frequently Asked Questions
Q: What are the advantages and disadvantages of the RS485 serial bus?A: The RS485 serial bus specifies a differential electrical interface form, and its standard adopts differential lines for signal transmission. If one line is in the logic 1 state, the other will be in the logic 0 state. Since the voltage circuit is bidirectional and differential, it can suppress common-mode interference in the transmission circuit, greatly improving communication performance. This bus is mainly applied in scenarios where there are a large number of detectors, which are centrally distributed and far away from the control room.
Its advantages are: it transmits digital signals, enabling the transmission of commands between detectors and controllers, so it is relatively intelligent; and it facilitates wiring.
Its disadvantages are: there is no unified protocol between different devices, resulting in poor interchangeability; the system is relatively fragile, and sometimes the damage of one detector may cause the system to crash. Generally, branch lines transmit analog signals, and we usually use 2-wire 4-20mA signals or 3-wire 4-20mA signals; normally, 4mA corresponds to the lower limit of the measurement range, while 20mA corresponds to the upper limit of the measurement range.
Branch lines are mainly used in scenarios where there are a small number of detectors, which are not centrally distributed, close to the control room, and have high requirements for system safety. Their advantages are: the system is safe and reliable; the interchangeability of controllers in the industry is high; their disadvantages are: commands cannot be transmitted between detectors and controllers, so they are not intelligent enough; and wiring is inconvenient.
Q: What payment methods are available at Tianjin Youtai Technology Development Co., Ltd.?
A: For the payment methods we currently support, please refer to the following: 1. Telegraphic Transfer (T/T); 2. Cash; 3. WeChat Pay.