Td = time to detect and report all reportable Tags
= #P * (Tr + Tt) + (#S - #P) * Tn
3.4 DATA PROTOCOL
The data protocol utilizes ASCII characters for all data from the Interface and all control functions from
the host computer. Each message includes delimiters at the start and end of message. Delimiters used
for messages from the Interface are Line Feed (<LF>) at the start of message and Carriage Return
(<CR>) at the end of message. For Commands into the Interface, the start of message delimiter may
be either Line Feed (<LF>) or a left hand bracket ([) and the end of message delimiter may be either
Carriage Return (<CR>) or a right hand bracket (]).
The protocol allows the Interface to be connected to a variety of computer systems, printers and
terminals. Since special ASCII control characters are avoided, software in the host computer can be
written in higher level languages without the need for special device driver routines.
3.5 ISSUING COMMANDS TO THE INTERFACE
All commands must be issued in CAPS.
There are eight command types by which the Host Computer can control the operation of the Interface.
These commands are:
I INITIATE SELF TEST
A#### ASSIGN READERS
M# MODE CONTROL
B#### BUFFER RESET
T TRANSFER REQUEST
R REPEAT MESSAGE
K#### SET ACCESS KEY
S SYSTEM RESET
Each command has its own functions, discussed in the following sections, but they are all entered in the
same manner. Each command must be preceded by a Beginning of Message (BOM) delimiter and
followed by an End of Message (EOM) delimiter. The BOM delimiter can either be a Line Feed
(ASCII 0A hex) or left square bracket: [ (ASCII 5B hex). The EOM delimiter can either be a Carriage
Return (ASCII 0D hex) or right square bracket: ] (ASCII 5D hex). The two types of delimiters can be
mixed, i.e. [T<CR> is acceptable. Note that terminals that issue a <CR> followed by a <LF>
automatically send the BOM delimiter for the next command. The BOM delimiter is held for an
indefinite length of time so that commands can be entered with two keystrokes. The # character in the
list of commands represent data required for the associated command.
The Interface does not recognize backspaces or delete keys, but the BOM delimiter clears out any
already entered information. Therefore if a mistake is made while entering a command, it isn't necessary
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