Siemens Industry Online Support
Siemens AG
Entry type: FAQ Entry ID: 19296306, Entry date: 07/30/2004

SIMATIC LOGON: Error Message when Accessing Chipcard Reader

  • Entry
  • Associated product(s)

When using SIMATIC LOGON and a chipcard reader, and during the startup of the WinCC runtime there is the error message "COMx cannot be accessed". X represents the number of the COM port to which the chipcard reader is linked. How can I avoid this error message?

The error message only arises, if the chipcard is already inserted to the device, during the startup of WinCC Runtime. There probably is a driver conflict. Both SIMATIC WinCC and SIMATIC LOGON attempt to access the chipcard reader simulteanously. 

In this case verify the following settings:

  1.  The WinCC chipcard reader must not be activated in the control panel..
    Go to Start > Settings > Control Panel. Doubleclick the function "WinCC Chipcard Terminal:" and click the radio button "Terminal disabled".

Fig. 1: Deactivating WinCC Chipcard 

  1. In WinCC User Administrator, option "Login only via Chip card" must not be active.
    In WinCC Explorer, open User Administrator by a doubleclick and deactivate the function "Login only via chip card".

Fig. 2: WinCC User Administrator

Deactivate this function for the corresponding user group.

When using SIMATIC Logon we recommend using user groups only. 

  1. In Editor „Configure SIMATIC Logon “, as logon device, the chip card reader has to be set with COMx .
    Go to Start > Simatic > SIMATIC Logon > Configure SIMATIC Logon  > Logon device and activate the function "Logon via smart card reader". Set here the COM interface, to which the chip card reader is linked to.

Fig. 3: SIMATIC Logon Device

Now it should be possible to log in with chip card without error message

No matter whether or not there is an error message, only one alternative may be used: either logging on by chip card via WinCC or via SIMATIC Logon.
In case you installed SIMATIC Logon, but intend to use the chip card reader with WiNCC instead of SIMATIC Logon, the chip card reader in SIMATIC Logon has to be deactivated.
A detailed description on this is also available in the online help or the manual (Entry-ID: 17621063) of SIMATIC Logon.

Key Words:
Chipcard Reader


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