What is the difference between RS485 and Ethernet?
Many clients asked: Hey S4A, for the access controller, What's the communication port I need to take?
RS485 or Ethernet, For better to understand, we will explain it in this way:
While Ethernet is the most commonly used communication protocol among multiple types of devices, ranging from consumer gadgets to industrial devices, TIA/EIA-485 commonly known as RS-485 is still broadly used in industrial devices even if it is older than Ethernet. Let's see why it is still in use and why, at S4A,we decided to use it as the standard communication protocol for our devices, Network access controller, such as ACB-001, ACB-002, and ACB-004
Many people are often confused when dealing with communication standards. Often, terms like ''RS-485'', ''USB'', and ''Ethernet'' are interchanged as if they could be switched and do the same job. But in fact, the RS-485 standard is only a physical layer standard. It defines the electrical characteristics of the transmitter and the receiver. On top of that, an application layer must be used to handle stuff like device addresses, checksum, packet collision, master/slave topology, frame construction, etc. In the case of Ethernet and USB, these protocols define both the physical and application layer in their communication standard.
If you're lost at this point, let's make an analogy with human communications. As humans, we use our voice as a transmitter and our ears as receivers. This is our physical layer, the way we transmit information. Another example of a physical layer in our digital era could also be SMS that transmits our messages. It is still a physical layer from our perspective. The application layer in the case of humans is language. This is how we organize information. There are hundreds of them and even if they use the same physical layer, they are not necessarily compatible.
Ethernet (IEEE 802.3) is the most broadly used network protocol these days. It is also a serial communication standard. Since it is used in so many modern networks, the question is why hasn't it replaced RS-485 and its other variations (RS-232, RS-422).
When comparing RS-485 with Ethernet both of them have advantages and disadvantages. The major drawback of RS-485 is its limited communication speed which is maxed out at 10 Mbaud. RS-485 is designed for a master/slave topology. In this system, the master polls each slave waits for the response, and then polls the next slave. This allows a deterministic behavior by avoiding collisions of data packets. Ethernet however has no built-in methods to avoid data packet collisions. In applications like process control or robot control, for us, deterministic behavior is mandatory while the speed of communication is usually more than high enough. Communicating at lower speeds also has the advantage of being more resilient to the noise present in industrial environments.
Author: Written by Mrs Auguest Yu from S4A INDUSTRIAL CO.,LIMITED
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