Siemens Industry Online Support
Siemens AG
Entry type: FAQ Entry ID: 109764546, Entry date: 04/24/2019

How do you determine the access strings (node IDs) of data points of the certified OPC UA server of the SITOP PSU8600 and UPS1600?

  • Entry
  • Associated product(s)
It is necessary to know the access strings (node IDs) of the relevant data points to read and write values of a OPC UA server. The client needs these to query and influence the required data correctly from the server.

The data structure of the OPC UA server power supply system SITOP PSU8600 certified by the OPC Foundation and the uninterruptible power supply UPS1600 is generated dynamically at startup. For this reason the access strings of the data points can change. This happens, for example, when upgrading the firmware or when the system structure is changed. Therefore, each time you change the configuration of your power supply, it is necessary to update the access strings in the program of your OPC UA client. If you do not do this, it might happen that the client accesses the wrong data or none at all.

We will show you how to use the program "UaExpert" to determine the access strings of data points of your SITOP power supply system. We also provide an overview of the main data points of the OPC UA server of the SITOP UPS1600 with battery module UPS1100 and SITOP PSU8600 with buffer module BUF8600. This facilitates browsing the data points in the relevant main modules.

Requirements for accessing the OPC UA server 

  • The web server of the device must be enabled:
    Pay attention to the switch settings on the front of the devices:
    SITOP UPS1600 Restart of the device with the rotary coding switch setting on "REN" and "OFF".
    SITOP PSU8600 Restart of the device with the DIP switch setting on "REN" and "WEN" on the right.
    Further information about the switches is available in the area marked "Links for handling the devices".
  • The OPC UA server of the device must be enabled:
    If you have not yet enabled the OPC UA server with the configuration, you can do this on the web server of the SITOP PSU8600/UPS1600.
  • The OPC UA server does not support anonymous login:
    Before you can use the OPC UA server, with the web server you have to have to connect at least once with the SITOP PUS8600/UPS1600. For the first login you use the default login data (User: "admin", Password: "admin"). At login you will be requested to change the password. You use the new password to connect to the OPC UA server.
  • User rights assignment:
     As soon as a user other than the admin wants to connect to the OPC UA server, he has to have the right "...to execute special functions". You can create and manage users and rights via the web server of the SITOP devices.
  • The port of the OPC UA server has to be released:
    Make sure that the port that you use for communication with the OPC UA server is not blocked by your firewall. The default port is "4840". You can change this via the web server.

Links to information about how to handle the devices
Information about how to handle the web servers, OPC UA servers and the user administration of the devices is available in the manuals at the following links.

Browsing the node IDs with "UaExpert"
How to determine the node IDs using the "UaExpert" program of an OPC UA server of the SITOP devices is explained in the following document.
  109764546_SITOP_Browsing_UaExpert_en.pdf (955,5 KB) 

Data structures of the various OPC UA servers
To help you with the browsing, the following figures give an overview of the OPC UA data structures SITOP UPS1600 and PSU8600 each with another module. These overviews shows the main data points for reading and writing and useful methods.

The nodes are arranged in alphabetical order within a level of the data structure.

  • UPS1600 with UPS1100

    Fig. 1

  • PSU8600 with BUF8600

    Fig. 2

Further Information
More useful information about OPC UA and the SITOP devices is available at the following links:

  • "SITOP power supplies - use of OPC UA in the SITOP environment", Entry ID 109750327
  • "Creating of OPC UA clients with .NET and helper class", Entry ID 109737901
  • "SITOP Power Supply Systems in the Online Support", Entry ID 109748829

Additional Keywords
Remote, Remote access, Web page, Uninterruptible, Network, Power supply unit, Supply, Power, CNX, BUF, BAT, Buffer, Battery, Distribution, Communication, Name space, Identifier type, Identifier

Security information
In order to protect technical infrastructures, systems, machines and networks against cyber threats, it is necessary to implement – and continuously maintain – a holistic, state-of-the-art IT security concept. Siemens’ products and solutions constitute one element of such a concept. For more information about cyber security, please visit