Question

Discuss the use of the RS-485 repeater.

Answer 1

RS-485 is a serial interface data transfer standard that solves the limitations of standard serial ports and enhances the data transfer to a greater distance and higher data transfer rates than the common non-differential serial repeaters. It uses a two-wire connection and can be used in all common 2-wire bus systems.

This RS-485 repeater is very convenient for multi-point interconnection and it can be used to reduce many signal lines. The applications of an RS-485 repeater can be grouped to form a distributed system that can allow up to 32 transfer drives and 32 receivers which can be connected in parallel. The new standard RS-485 has the following uses:

1. Supports all popular 10/11-bit UART data formats
2. It supports the transmission speeds from 1.2 kbps up to 1.5 Mbps
3. There is High-quality 3-way isolation between all interfaces
4. It is space-saving that has a slim thickness of 22.5 mm device
5. It has an automatic transmit/receive changeover
6. Advantage of Integrated, connectable termination resistors
7. Integrated surge protection enabled with the transient discharge to the DIN rail
8. Plug-in screw connection terminal blocks
9. The electrical characteristics of RS-485 include the following: The logic “1” is represented by the voltage difference between the two lines of distribution +2V~+6V, and the logic “0” is represented by the voltage difference between the two lines of distribution -6V~-2V. The interface signal level is lower than that of RS-232-C repeater, and this doesn't easily damage the interface circuit chip, and this level of rs-485 signals is compatible with the TTL level, which is suitable for the connection with the TTL circuit.
10. The RS-485 repeater interface adopts a fusion of balanced driver and a differential receiver that has a strong anti-common mode overlapping capability, which enables a good anti-noise performance.
11. The maximum possible transmission distance of the RS-485 repeater interface is nearly 4000 feet(3000 meters).
12. The RS-485 repeater allows up to 128 transceivers that can be connected to the bus(multi-station capability). This enables the user's device network to be easily installed using a single RS-485 repeater.