SECTION 5 - DATA COMMUNICATIONS PROTOCOL
EXAMPLE OF CHECKSUM COMPUTATION:
Block chars
ASCII Hex values
<STX>
02
0
30
1
31
2
32
<CR>
0D
A
41
В
42
C
43
<CR> 0D
<ETX> 03
178 Hex 1+30="1", Hex 7+30="7", Hex B+30="8"
A complete block would then be: "<STX>123<CR>ABC<CRxEXT>178<CR>"
The Acknowledgements take one of four forms:
<ACKxCR>< optional xCR> Received block is accepted, send next
or
<NAKxCR>< optional ><CR> Received block contains a checksum
error, retransmit it
or
<RSxCR>< optional ><CR> Received Transaction or block contains
an invalid < pager field >, or the last
block has been transmitted 3 times with
a checksum error each time
or
<ESCxE0T>< optional xCR> Paging Terminal has disconnected
DISCONNECT
The Entry Device will terminate the transfer of all Transactions with
"<EOTxCR>". This will signify that the Entry Device has finished
transferring all of its paging data and that the Paging Terminal may
disconnect.
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