User's Manual

Message Format
Transponder PT21 Messages B-1
Appendix B
Transponder PT21 Messages
Message Format
Each message has the following format
where:
Prmbl = 0.7 ms continue 1.
Sync = a string of 10 bits of “0101010101”.
Start = a string of 13 bits “0101010000111”.
SC = 2 bytes system code; transmitted only if TS=Y.
UD = user definable data; number of bytes is set by CC (1 to 32).
GateID = 1 byte with received gate ID.
Cntrl = 1 control byte.
CRC = 2 bytes CRC; transmitted only if EC=Y.
Flag = 2 bytes message flags; transmitted only if TF=Y. It has 1 byte if HF=N and 2 bytes if
HF=Y.
Key = 1 byte message key; transmitted only if EN=Y.
PT21 Parameters The parameters that control the message transmission for PT21 are shown in the table below:
Total Transmission
Time
After a valid excitation, the PT21 transmits the initial number of messages defined by the IP
parameter, followed by an extra number of messages (up to the RC) for as long as the excitation
exists. Then it goes to sleep.
Parameter Range Description
DR 4 Data rate; DR4= 38.4 kbps
EC Y/N Standard error check transmitted
EN Y/N Data encryption available
HF Y/N Flags in hexadecimal
ID 0...200 Initial delay
IP 1...200 Initial number of messages transmitted after a valid execution
LT Y/N Limit repeated transmissions
RC 0...255 Number of extra messages transmitted after IP during a continuous excitation
RS 0...255 Random seed
SD 1...220 Subsequent delay
TF Y/N Transmit Flags
TS Y/N Transmit System Code
SYNC START SC UD GateID Cntrl CRC KEY FLG