V1040 RS485

[JohnnyB]

Hi Guys.

What max devices i connect in a RS 485 port ? - In the Unitronics Manual ( Unitronics Devices and RS485 pg 3) say:

"RS485 is a balanced serial interface for the transmission of digital data, which enables you to

create a multi-drop network containing up to 32 devices, or nodes"

In TIA/EIA-485 (RS-485) have information about unit load and other information about the max nodes.

It is possible following some specified increase the number of nodes? (+ 32)?

[JohnnyB]

In time, In the datasheet of module that I use have an information :

Unit load: 0.125.

[linxchas]

It is not quite right to say that RS485 is limited to 32 nodes. The standard limits the number of nodes to 32 on one wire segment. If the network is extended by repeaters into multiple wire segments each segment can have up to 32 nodes. There is nothing said how many segments you can connect but of course there will be a practical limitation somewhere.

Here is repeater we were using: http://rs485.com/pmhubx8.html

[Emil]

The standard says 32 notes. Then:

1. If you're making very good network, maybe you can put more nodes. I know people are doing it. There is no direct technical limitation. In other hand, there is no prove the network wil work properly.

2. You can use repeaters, like in te post below. This is normal, standard solution.

3. You can divide the network and connect the nodes to more than one COM port.

This last soluiton has thhe advantage, that the polling time pre node will be shorter, than in the solution No.2.

Again, it depends on thhe specific needs of your project. If you are ready to share them, I hope there will be members of this forum, which will be glad to share their experience.