User's Manual

REFERENCES
55
5
Host with
Bluetooth
®
device
NACK
data
GRYPHON



BT
data
good RX
beep
A
CK
ACK/NACK enabled
When ACK/NACK is enabled, the Host sends an ACK character (06 HEX) in the case
of good reception or the NACK character (15 HEX) requesting re-transmission, in the
case of bad reception. Only after the ACK character is received by Gryphon™ BT
SH3500 does the reader respond with the good reception tone.
If the reader does not receive an ACK or NACK, transmission is ended after the
Radio Protocol Timeout, par. 5.2.1.
Frame Packing
When Frame Packing is disabled, the Output Message
from the Gryphon™ BT
SH3500 reader is sent to the Host as is, see par. 5.1.
If instead, Frame Packing is enabled, the Output Message is "packed" into a Frame
with the following format:
STX Length Control Counter Output Message CRC-16 CR
where:
STX = Frame Start character (02 Hex).
Length = 2 bytes; indicates frame length of the remaining fields (including CR).
Control = 1 byte; indicates message fragmentation. For further details see the DL
Security Protocol documentation on the CD-ROM.
Counter = a loop counter for the Output Message characters (bytes) that cycles from
0 to 255 and then restarts.
Output Message = complete text message from the Gryphon™ BT SH3500 reader
including optional fields as shown in par. 5.1. The maximum length of this field is 304
bytes.
CRC-16) = 2 bytes; 16-bit Cyclic Redundancy Check based on the hex 1021
polynomial and performed on all bytes from Length up to the CRC itself. The MSB is
sent first. For further details see the DL Security Protocol documentation on the CD-
ROM.
CR = Frame Stop character (0D Hex).