If guest cards can no longer open room or entrance doors, there may be several reasons for this. The most common cases are as follows:

• Clock problem
• Generation error
• Battery warning
• Missing access rights
• Faulty clutch

In general, it is very helpful to find out why a guest card is being rejected. There is a method for reading out an error code on almost all terminal types. This method works in both the DG1 and DG2 systems with guest and staff cards.
NOTE: With old DG1 terminals (e.g. DTv6, DTSH) it is not possible to read out the error code using this method.

To read an error code using a rejected card, it must be held in front of the terminal (door reader or wall reader) for a longer period of time - approx. 5-10 seconds. It should first beep twice and flash red when held for a short time. If you continue to hold the card in front of the reader, the terminal will display an error code in the form of beeps and flashes.
If you count these carefully, you can use the error code list to determine why a card is being rejected.

If the guest card is not rejected at all and the terminal accepts the card (white, green or blue LED lights up), then there is probably a clutch fault.