Development of domestic parking guidance system
2023-10-06 00:00:00
a, RS232 bus
the RS - 232 - C is the EIA of the Electronic Industry Association (Electronic Industry Association to develop a serial physical interface standard.RS - 232 - C bus standard has 25 pair of signal lines, including a main and an auxiliary channel, in most cases the main use of main, for general duplex communication, just need a few signal can be realized, as the sending wire, a receiving line and a ground wire.The RS - 232 - C standard stipulated by the data transfer rate of 50, 75, 100, 150 per second, 300, 600, 1200, 2400, 4800, 9600, 19200, potter.RS - 232 - C standard regulation, drive allows 2500 pf the capacitive load, communication distance will be restricted by the capacitance, for example, using 150 pf/m communication cable, the maximum communication distance of 15 m;If per meter cable capacitance decreases, and increases communication distance.Transmission distance is short of another reason is that the RS - 232 is a single-ended signal transmission, have common ground noise and can not restrain common mode interference, so commonly used in communications within 20 m.Its defect is common mode rejection ability is poorer, less susceptible to interference, the transmission distance.
2, RS485 bus
the RS485 bus is way of communication is often used in the parking lot system, RS - 485 using balance send and difference to receive, so has the ability of restrain common mode interference.Plus bus transceiver equipment has high sensitivity, can detect low voltage to 200 mv, so the transmission signals can be outside the km restoration.Using RS - 485 half duplex works, there can be any time point in the sending state, therefore, sending circuit must be controlled by the signal.The RS - 485 for multipoint connection is very convenient and can save a lot of signal lines.The application of RS - 485 can form a distributed network system.Its advantage is easy to wiring.Technology mature and stable transmission distance is farther.
3, TCP/IP protocol
the TCP/IP is a network communication protocol, and is the foundation of the modern Internet, application is very wide, due to the development of technology, is now widely used in the parking lot system, just as an aside, our company parking system is mostly use this agreement.TCP (Transmission Control Protocol) he is Transmission Control Protocol (TCP), IP (Internet Protocol) is a network interconnection agreement.TCP/IP way of searching for the Internet host address, host name mechanism, information transmission rules, as well as a variety of services have made detailed provisions.IP is responsible for will need to transfer information into a lot of packets, and will these packages sent to the destination, each packet sent to the destination of the packet contains the part to the transmission of information, also contains the address of the destination you want to, and other important information.TCP is responsible for managing the packet transmission, automatic detection lost in the transmission of information and automatic recovery, ensure the effective and reliable transmission.Communication distance, fast transfer rate is its characteristic.
4, wiggins (wiegand) protocol:
this agreement had less contact, but it is not very understanding, have a look at it, it is good to know.Wiggins (wiegand) agreement is a common communication protocol, common with wigan, wiggins 34, 26 theoretical transmission distance of 120 meters.Standard wiggins output is composed of 26 bit binary number, the meaning of each are as follows: 1 to 2 & ndash;13 the parity bit 2 & ndash;Nine low 8 bits that corresponds to an e-card HID codes corresponding to an e-card PID number 10-25 26 for 14-25 odd parity bit.
well, about parking system several kinds of communication way is introduced to this, we hope to help you, thank you for your last reading.