MagTek HALF CARD PORT - Manual (Page 11)

Section 1. Features and Specifications
3
MODES OF OPERATION
The Reader can operate in either unbuffered or buffered mode. The modes are described below.
The note that follows applies to both modes.
Note
The insertion and removal of the card must be done in a
continuous motion. If not, the Reader may not read the encoded
data properly. In that case, the Reader responds by either
transmitting the ASCII character “E” representing an error, or by
not transmitting any character, which indicates that the Reader
has not detected data and the card was not completely inserted.
Unbuffered Mode
When a card is inserted and removed, a read attempt is made during both insertion and removal.
If the read is successful, data (including the two sentinel characters) is sent to the PC. The data
is transmitted immediately after removing the card and not retained in the Reader.
When operating in the unbuffered mode, the Reader does not need to receive commands from the
host in order to transmit data or status characters, and data, if available; however, the Reader
does respond to an “Inquiry Command” by sending status characters. The inquiry command that
requests the transmission is the ESCAPE (ESC) character followed by “I” (0x49).
In the unbuffered mode, data can be retrieved from the card after the card has been inserted and
while it is blocking the rear sensor. Issuing an “Inquiry Command” (see Section 3) will retrieve
data from the card.
Buffered Mode
When a card is inserted and removed, a read attempt is made during both insertion and removal.
Upon removal of the card if the read is successful, data (including the two sentinel characters) is
stored in a memory buffer on the Reader and is not transmitted until the Reader receives an
“Inquiry Command” from the host. This command is the ESCAPE character followed by “I”.
The data or error status is available when the back sensor is blocked, however the Release
Command will not clear the buffer. The Reader cannot read another card until the buffer is
cleared. To clear the buffer, the Host must transmit the ESCAPE character followed by “R”.
The unit will always output a 1 and enabled optional characters when the back sensor is first
blocked. It will output a 0 and enabled optional characters when the card has been withdrawn.
See Section 3, Table 3-4 for detailed examples.