Which card uses a plain-text mechanism to pass the credentials between the reader and the control panel?

Magnetic cards store data on a magnetic stripe that requires a magnetic reader to decode the information. The data is typically encoded in a format that is not plain-text and often includes encryption for security purposes, making it less accessible than the plain-text format used by bar-coded cards.

Proximity cards utilize radio frequency identification (RFID) technology to transmit data wirelessly when brought near a reader. This communication is generally not in plain-text format, as it often involves encrypted signals to enhance security and prevent unauthorized access, differing fundamentally from the straightforward nature of bar-coded cards.

Wiegand refers to a data format commonly used in access control systems for transmitting information from a card reader to a control panel. While Wiegand can convey card data, it does not operate on a plain-text mechanism. Instead, it relies on a specific binary encoding that transmits the data in a less transparent manner compared to bar-coded systems.