Determine serial online connection parameters (SG3 legacy systems)

Most often, B&R’s legacy PLCs (the so called SG3 PLCs out of the system families 2005, 2003, PowerPanel 15/35 and so on) use a serial connection to communicate with Automation Studio (mostly used with the legacy Automation Studio Versions 2.x and 3.x).

This post summarizes some basic information about legacy serial online connections (already written here and there in some posts of our Community), and a idea how to determine the serial online settings if they’re unknown.

First, here’s a summary of some basic information about a serial connections:

  • this legacy serial online protocol is called “INA

  • the default online parameters are 57600 Baud, 8 Databits, 1 Stop Bit, Parity Even

  • the developer can change this settings inside the project → so the default is only valid if parametrization of the serial online interface wasn’t changed

  • the developer can use the serial interface(s) for his own task → that means, if for example the developer creates a function to communicate via serial interface to a 3.rd party device and the PLC executes this code, maybe the online connection does not work.

  • the INA connection doesn’t use hardware handshake → the serial online cable only needs RX, TX, and GND pins connected in the right way. For example, on a 9 pin D-SUB socket the online cable has to have following pins connected:
    2 → 3
    3 → 2
    5 → 5

  • More information, like how to setup in the PLC and in Automation Studio, can be found here in the online help

If you need to go online with a serial connection but the default parameters don’t work, then you have to probe the different settings to find the right parameter set (or even to find out that the online connection is not possible at all because the developer has switched it off).

To “automate” this probing a bit, you could use the Runtime Utility Center (RUC) and create a “srcipt” that probes different serial online parameters.
(RUC is part of every Automation Studio installation, actual versions of RUC are part of the Automation Net/PVI Development Package and can be downloaded / upgraded via the B&R hompage)

I created a example for such a RUC instruction list (*.pil file), that is probing different serial settings.

Please note, that the example doesn’t probe every combination of serial parameters possible, but the “common ones” (see below).

How to use:

  1. download the zip file (which includes only the pil file)
    TestSomeSerialConnectionParameterVariants.zip (716 Bytes)

  2. open the pil file with a editor, and replace the com port COMx (in this example: COM8) with the com port you have

  3. open and execute the pil file with RUC

  4. while running, RUC will try to detect a online connection with probing the parities Even,Odd,None using the baudrates 115200,57600,38400,19200 (always using 8 data bits and 1 stop bit).
    If a connection is established, a popup will appear and the execution ends:


    If no connection is found, the execution ends with a error popup:

That’s it! :wink:

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