What kind of communication is RS-485?

RS-485 is a duplex communication system in which multiple devices on the same bus can communicate in both directions. RS-485 is most often used as half-duplex, as shown in the figures above, with only a single communication line (‘A’ and ‘B’ as a pair).

Is RS-485 a communication protocol?

RS-485 is used as the physical layer underlying many standard and proprietary automation protocols used to implement industrial control systems, including the most common versions of Modbus and Profibus. DH 485 is a proprietary communications protocol used by Allen-Bradley in their line of industrial control units.

How does 485 communication work?

In RS485 standard, data is transmitted via two wires twisted together also referred to as “Twisted Pair Cable”. The twisted pairs in RS485 gives immunity against electrical noise, making RS485 viable in electrically noisy environments. RS485 at its core with 2 wires allows half-duplex data transmission.

How do you troubleshoot RS-485 communication?

Troubleshooting RS485 / Modbus RTU Wiring

  1. Check that communication settings parameters are correct (baud rate, etc).
  2. Check that the slave address matches with the id assigned in data logger.
  3. Check modbus wiring.
  4. Check for reversed polarity on RS485 lines. If uncertain, just try swapping them.

What is the difference between RS485 and CAN bus?

The main difference is the bus arbitration of CAN, which means that the network topology is flexible and there is no need for a master to control traffic. In RS-485 there is no built-in mechanism to toggle who gets to send, meaning that RS-485 tends to end up in a star network topology centred around a master.

What are the advantages of RS485?

The RS485 has many advantages over both RS232 and USB when it comes to applications in noisy industrial environments. It was designed from the beginning to be tolerant of noise and forgiving of long cable runs. It achieves this by using a differential current drive output which has high immunity to noise.

Can I connect RS485 to Ethernet?

By converting RS485 data signals into Ethernet (TCP or UDP) packets, and vice versa, they enable reliable data transmission to other devices or network server applications. This is accomplished by encapsulating the RS485 data in Ethernet packets in a manner that best fits the type of data being transported.

Can you use Ethernet cable for RS485?

cat5e can be used up to 100m ethernet link. it has 4 twisted pairs so technically you should be able to use it for RS485 or RS422. if using 485, you need two twisted pairs so remaining 4 wires can be used for power. 485 cable should be shielded but twisted pairs of cat5e may work for some environments and baud rates.

How do I know if my RS485 port is working?

To check if your RS232 to RS485 converter (or USB to RS485 converter) is working properly you can make a loop-back test using a terminal program such as AccessPort. This way you can determine if the converter can send and receive characters properly.