RS 485 connections to terminals using the HMI Editor

FAQ #100136

Traditionally terminals were connected to the HMI Editor via RS 232 with Handshake, which is still the safest way. If more than one terminal has to be put on the same line or when the terminals are at large distances you can create RS 485 networks, but there are some restrictions. If you need only one terminal but at a large distance, RS 422 is the best choice as it offers the same functionality as when using RS 232.


To create an RS 485 network of terminals using the HMI Editor, procede as follows:

  • choose a terminal that supports RS 485, for instance the PCD7.D23x. The PCD7.D79x terminals can as well be connected via RS 485, but as they don't have an automatic key repeat function, it is tedious to change setpoints with these terminals, so the PCD7.D23x are the better choice
  • configure the station address and baudrate in the setup of the terminal(s)
  • choose the "bus terminals" topology in the HMI Editor
  • define all terminals using the same addresses as you configured before
  • define the standby, busy and login menus

When working with the "bus terminals" topology the dialogue on the terminals is as follows:

  • all terminals display the standby menu per default
  • when the user pushes a button the relevant terminal goes to the login menu, all other terminals go the busy menu and cannot be used until the terminal in use is freed
  • the login screen can contain the entry of a password. After entering the password the terminal goes into the "normal" menu structure


Local FAQ Deutschland / HMI Editor

Last update: 29.05.2015 07:26

First release: 15.06.2004 08:27

Views: 14749

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