The interface signal level is lower than that of RS-232-CIt is not easy to damage the chip of the interface circuit, and the level is compatible with the TTL level, which can be easily connected with the TTL circuit. The maximum data transmission rate of RS-485 is 10Mbps. The RS-485 interface is a combination of balanced driver and differential receiver, and the resistance to common mode dry is enhanced, that is, the anti-noise interference is good.
interface signal level value is high, easy to damage the chip of the interface circuit, and because it is incompatible with the TTL level, it is necessary to use the level conversion circuit to connect with the TTL circuit. (2) The transmission rate is low, in the asynchronous transmission, the baud rate is 20Kbps.
The complete model is BF422, fT60MHZ, BVceo250V. It is the final stage of a universal television set. There are many triodes that can replace 422. The main need to meet: fT50MHZ, BVceo200V (the most important indicator: must be greater than the power supply) of the NPN triode. But in the assembly should pay attention to the separation of pins.
Support RS422 interface core chip (MAX488, MAX490; MAX489, MAX491) RS422/RS485 interface chip is known as follows: Product comparison: RS422 is a four-wire dual port (two-wire receiving port and two-wire sending port). There's only one owner. The sending port of the host is connected to the receiving port of all the slaves.
HYM48HYM48HYM48HYM487-HYM491 and HYM1487 are low power transceivers for RS-485 / RS-422 communication.
The chip acts as a differential driver chip, and each channel outputs a set of complementary outputsThe Y and Z signals. This group of signals can be directly connected to other differential receiver chips for signal conversion and transmission. Post-drive can also be performed, such as drive optocoupler.
rs422 to ttl level chip. RS422 extension interface to TTL level chip and Ethernet module.
Yutai USB to RS422/485 is the chip used on UT333S, laser lettering is UT232s, actually is 74HC08 (and gate), the function is to receive the signal of 485 and 422 two working modes and then send to FT232RL corePieces.
1, LocalBus bus connection, crystal circuit and UART chip connection. The invention needs to solve the technical problem is to provide a multi-channel serial communication method, which can conveniently realize the multi-channel serial communication task in real-time embedded system, and improve the efficiency of system development and debugging on the basis of reducing the consumption of bus resources.
2, UART is a universal asynchronous transceiver, is a serial communication protocol, it specifies serial communicationBaud rate, start/stop bit, data bit, check bit and other formats, as well as a variety of asynchronous handshake signals. RS232 is a physical interface electrical standard for serial communication, which stipulates that the transmission medium (cable) and the receiving power generation are equal.
3, because the RS485 interface composed of half duplex network, generally only two connections, so the RS485 interface are shielded twisted pair transmission. The RS485 port connector uses the 9-pin connector of the DB-9, the DB-9 (hole) port of the RS485 port connected to the smart terminal, and the DB-9 (pin) port of the RS485 port connected to the keyboard.
4, support RS422 interface core chip (MAX488, MAX490; MAX489, MAX491) RS422/RS485 interface chip is known as follows: Product comparison: RS422 is a four-wire dual port (two-wire receiving port and two-wire sending port). There's only one owner. The sending port of the host is connected to the receiving port of all the slaves.
5, the meaning of the register Register is a part of the central processing unit. Registers are high-speed memory components with limited memory capacity. They can be used to temporarily store instructions, data, and addresses. In the centerThe control unit of the manager contains the instruction register (IR) and the program counter (PC).
Generally yes, grounding is to reduce electromagnetic interference. In particular, chips such as single-chip computers, when conditions permit, try to apply copper and connect with the formation. Of course, not grounded, in the general environment, has no effect on the operation. The industrial environment needs more consideration.
Simple star topology, tree topology and even mixed topology sometimesIt can be used, but the communication will certainly be unstable, if you must deploy the star, tree topology, it is recommended to use 485 hubs and 485 Repeaters, related applications can refer to the 485 bus topology problems page.
Must. The casing is also known as safe, safe casing. To ensure the safety of equipment and personnel, the grounding system is established between the equipment housing and the ground potential.
1, refers to different RS-422: is a series of provisions using 4-wire, full-duplex, differential transmission, multipoint communication data transmission protocol. RS-485 is a standard that defines the electrical characteristics of drivers and receivers in balanced digital multipoint systems. RS-232: is one of the commonly used serial communication interface standards.
2, the maximum communication distance of RS232 is 15 meters, and the maximum communication distance of RS422/485 is 1200 meters. Number of connected devices RS232 can be connected to only one device, while RS485 can be connected to multiple devices.
3, transmission speed: RS232 interface transmission speed is relatively slow, suitable for low-speed data transmission, such as control commands and configuration information. Distance limitation: Due to the influence of signal attenuation and interference, the RS232 interface is limited in the transmission distance and is generally not suitable for long-distance transmission.
4, simply said RS232 is full duplex, RS485 is half duplex, RS422 is full duplex.
5, RS-232, as the earliest standard, is used for short-distance (within 13 meters) serial port connection between devices. The baud rate is selected against the transmission distanceAnd anti-interference is crucial, usually use 5 line, standard configuration within 3 meters. Its limitations mainly lie in the single point of communication, and it does not support multi-device networking.