MagTek P-SERIES USB - Manual (Page 24)

P-Series USB Insertion Reader
16
TRACK DATA
If decodable track data exits for a given track, it is located in the track data field that corresponds
to the track number. The length of each track data field is fixed at 110 bytes, but the length of
valid data in each field is determined by the track data length field that corresponds to the track
number. Track data located in positions greater that the track data length field indicates are
undefined and should be ignored. The HID specification requires that reports be fixed in size,
but the number of bytes encoded on a card may vary. Therefore, the Input Report always
contains the maximum amount of bytes that can be encoded on the card and the number of valid
bytes in each track is indicated by the track data length field. The track data is decoded and
converted to ASCII. The track data includes all data starting with the start sentinel and ending
with the end sentinel.
TRACK 1 DATA
This field contains the decoded track data for track 1.
TRACK 2 DATA
This field contains the decoded track data for track 2.
TRACK 3 DATA
This field contains the decoded track data for track 3.
CARD STATUS
Bits 7-1 0
Value Reserved Card Inserted
This is a one-byte value, which indicates the card status. Bit position zero indicates that the card
was swiped in the insertion direction if it is set to one. If it is set to zero, then the card was
swiped in the withdrawal direction. All other bit positions are reserved.
COMMANDS
Most host applications do not need to send commands to the device. Most host applications only
need to obtain card data from the device as described previously in this section. This section of
the manual can be ignored by anyone who does not need to send commands to the device.
Command requests and responses are sent to and received from the device using feature reports.
Command requests are sent to the device using the HID class specific request Set_Report. The
response to a command is retrieved from the device using the HID class specific request
Get_Report. These requests are sent over the default control pipe. When a command request is
sent, the device will Nak the Status stage of the Set_Report request until the command is
completed. This insures that as soon as the Set_Report request is completed, the Get_Report
request can be sent to get the command response. The usage ID for the command message was
shown previously in the Usage Table.