Question: What is the maximum distance for RS-485 communication? Are there any devices or methods that can increase the distance?
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In ongoing projects, it is necessary to connect all the flow meters using RS-485 communication. However, there are a large number of flow meters, and they are spread out over a wide area; forming a single circuit in this case would require an extremely long distance. May I ask what the distance limit (maximum distance) for RS-485 communication is? What is the definition of this limited distance as well? Does it refer to the total distance of all the segments combined? Or does it refer to the distance between each flow meter? Also, are there any devices that can increase this distance? Thank you!
I used over 800 meters on-site with no issues; it’s possible to use RS485 to convert to TCP and then transmit over fiber for 25 km
At most, it should be able to transmit over 1200 meters
Your ongoing projects must be really exhausting. This communication scheme is simply a mess.
You can go as far as you want; just add a relay for that. Single-mode fiber.
1200 meters of shielded twisted pair is no problem. With too many points, wiring needs to be taken into consideration. If real-time performance and confidentiality are not high, it would be great to use a wireless module powered by solar energy.
1. The RS485 bus: each slave device is connected in parallel to the two buses. 2. For the farthest distance from the lower-level device to the upper-level device, this can be considered as the actual distance of the bus. 3. With a communication baud rate of 9600, the actual transmission distance of the signal is approximately 200 meters. 4. At a baud rate of 1200, the communication distance can be around 1200 meters. 5. The maximum distance that can actually be achieved is related to the number of master and slave devices on the bus, the quality of the cables, and the quality of the slave devices themselves. 6. If the distance is too great, a 485 repeater can be used; switching to fiber optics makes it even more reliable. 7. Wireless methods: In situations with lightning, thunder, strong winds, and heavy rain, their reliability is questionable; they are generally not suitable for use in control systems, but only for simple monitoring systems.