RS485 main advantages as compared to other serial communication are tolerance to electrical noise, lengthy cable runs, multiple slaves in one connection, and fast data transmission speed. Just like it’s older brother RS232, RS485 is a form of serial communication. RS485 provides a means of interconnecting multiple devices in a series using a twisted pair of wires to facilitate data exchange. RS485 is the most versatile communication standard in the standard series defined by the EIA, as it performs well on all four points. With RS485 communication distances of 1200 m are possible. The maximum RS485 cable length is typically listed as 1200 meters or about 4000 feet. RS232 is an interface to connect one DTE, data terminal equipment to one DCE, data communication equipment at a maximum speed of 20 kbps with a maximum cable length of 50 feet. You aren’t limited to fifty feet of cable like with RS232. Much like RS232, RS485 doesn’t have an actual standard connector.
RS-485, like RS-422, can be made full-duplex by using four wires. The greatest feature of RS485 is the fact that you can connect up to 32 devices on one system. Stable connections play a crucial role in managing and controlling access to secure areas, optimizing system performance. Within such a system, RS-485 serves a pivotal role as a bridge, establishing communication of flow information between the central control system and each valve box. Insulation/separator layer: This layer plays a role in insulation and enhances the durability and lifespan of the cable. The left side of the image shows the structure of the twisted pair cable, including copper wire, shielding, and insulation. Common standards: RS232 RS422 RS449 RS485 20 mA current loop Serial data transmission standards including RS232, RS422, RS423, and RS485 were widely used for many data links, proving effective connectivity for the day. RS232, RS422, RS423 and RS485 are serial communication methods for computers and devices. Manufacturing facilities use serial communication to link their devices together. This allowed users in manufacturing facilities to connect larger applications and whole machines with one protocol. That is why RS485 is currently a widely used communication interface in data acquisition and control applications where multiple nodes communicate with each other.
It is the reason why RS485 is so popular with computers, PLCs, micro controllers and intelligent sensors in scientific and technical applications. Now, why don’t companies just use USB or ethernet to transmit data between their devices? RS232 RS-232 is the most widely used serial standard that is in use. The standard is jointly published by the Telecommunications Industry Association and Electronic Industries Alliance (TIA/EIA). This standard is a product of joint efforts by the Telecommunications Industry Association and the Electronic Industries Alliance (TIA/EIA). There is no standard connector for the protocol. RS485 is a hardware architecture that specifies only the electrical characteristics of transmitters and receivers, without endorsing any particular transmission protocol. DH 485 is a proprietary communications protocol used by Allen-Bradley in their line of industrial control units. What made it such an advancement over RS232 was the fact that it could transmit not only a single device to device transmission, but also a communications bus to connect multiple devices at once. Control and monitoring systems: A single pair of rs485 signal cable can connect up to 32 devices, with a signal transmission distance of up to 1200m. Therefore, using rs485 cables is an ideal choice for industrial control and monitoring systems, especially those with large-scale and high dispersion.
The characteristic feature of the Daisy Chain topology is the sequential connection of each device along a single line, what is rs485 cable not forming a loop structure. Another major advantage is that there can be more than one slave in the connection. Another advantage over RS232 that I mentioned earlier is the number of connectable devices. Although a number of different wires were often used within a cable, they did not require nearly as many as the systems that sent parallel data. The diagram below shows potentials of the A (blue) and B (red) pins of an RS-485 line during transmission of one byte (0xD3, least significant bit first) of data using an asynchronous start-stop method. The configuration and specifications of RS485 make it faster and extend the range of data transmission. This means data can be transmitted in both directions to and fro devices one direction at a time. You can also still simply use a terminal strip.