SECTION 5 - DATA COMMUNICATIONS PROTOCOL
PAGING DATA TRANSFER
Once Logon is complete, the transfer of paging data can begin. An
indefinite number of Transactions can be transmitted to the Paging Terminal,
as long as no errors occur which cause the Paging Terminal to disconnect.
Such errors would include incorrect block structure, receipt of <E0T>, and
timeouts. Timeouts occur 6 seconds after the receipt of the last character,
but timeouts can be disabled for the Serial I/O port through programming
(see "System - Communications").
Data Transfer occurs in structured blocks of 256 or fewer characters. Each
block must be acknowledged by the Paging Terminal before the next block can
be sent. A Transaction is defined to be a complete pager field and a
complete message. One or more blocks may be required to transmit an entire
Transaction.
The Paging Data Transfer Sequence is:
Entry Device
Paging Terminal
"<STX>
< pager field ><CR>
< message ><CR>
<ETXxchecksumxCR>"
or
"<STX>
< pager field ><CR>
< message ><CR>
<ETBxchecksumxCR>"
acknowledgement
"<STX>
< message x C R >
<ETBxchecksumxCR>"
Comments
This form is used for pages
with short to moderate length
messages. <ETX> indicates that
this Transaction is complete.
Pages with very long’ messages
may require more than one
block to be transferred, but
the < pager field > is sent
only once. <ETB> indicates
that there is another block
to come before this Transaction
is complete.
acknowledgement
"<STX>
< message x C R >
<ETXxchecksumxCR>"
The final block of the
Transaction is terminated
by <ETX>.
The < paging field > takes one of two forms, depending on the Data Transfer
mode. For the Internal Data Base mode, the form is:
< paging field > = xxx
where xxx are one to four ASCII digits
that form a number within the range of
valid User numbers for the Paging
Terminal (either 0-99, 0-399, or 0-1199)
5-3
