The reader responds to the access card, but its code is not displayed in the system.

1. No resource is specified for the control point: Check if the Reader resource is available in the controller's control point settings.
   
2. The reader is connected to a different port or a different address is specified: Check the correct reader connection port or bus location address in the controller settings.
3. Incorrect connection: Check if the D1 and D0 data wires between the controller and the reader are connected correctly.
   
4. Unsupported format: Verify that the reader's Wiegand bit format matches the requirements and capabilities of the access control device. 
   

The card code displayed in the system after being read at one reader does not match the code read at another reader.

Tip: Swap reader connection ports to determine if the problem is caused by a specific port or wire. If the card code is still different, the problem may be due to an incorrect reader configuration. If the card code is the same after changing connection ports, the discrepancy in the displayed code may be due to the reader configuration settings in the controller settings.

1. The difference is in the order of code reading: Change the order of the reader configuration bytes in the controller settings.
   
2. The D1 and D0 data transmission wires are misplaced: Check that the D1 and D0 data wires are correctly connected between the controller and the reader.
3. Reader configurations are different: If the reader has a configuration menu, make sure that in its settings, parameters such as Wiegand bit format and byte order match the reader on which the card code is read correctly.
4. Combined card is used on readers with different formats: Make sure that a combined card with two frequencies (125 kHz and 13.56 MHz) is not used on readers that support different frequencies. If this happens, the card codes may differ when read on different devices.
   

Additional recommendations: If the problem occurs when the pin code is displayed, change the byte order in the controller settings. Note that on combination pin keypads with an integrated reader, changing the byte order may change the way access cards are read. It is recommended to use the same reader models throughout the facility to avoid differences in card code reading and eliminate possible confusion when working with the access control system.