text stringlengths 0 99.6k |
|---|
and the Initiator will abort cleanly. For this reason it is |
essential that any B Plus implementation observe the rules |
for <ENQ>: If in terminal mode, send <DLE> + + <DLE> 0; |
otherwise send <DLE> Sequence. |
17 |
E. Negotiation of Transport Parameters. |
The Initiator begins a B Plus protocol session by sending: |
<ENQ> |
while the Responder is in terminal mode. The Responder sets |
itself up for: |
o Standard Checksum |
o Default Quoting |
o 512 byte data block |
o Sets its Sequence to 0x30 (`0') |
o transmits the sequence: |
<DLE> + + <DLE> 0 |
o returns to terminal mode. |
The Initiator, detecting the `<DLE> + +', sends a Transport |
Parameters Packet using Standard Checksum and quoting of |
0x00 thru 0x1f and 0x80 thru 0x9f. When the Responder |
properly receives this packet, it must transmit a Transport |
Parameters Packet indicating its own parameter settings. |
Once the Initiator Acknowledges the Responder`s Transport |
Parameters Packet, each entity then establishes its |
operating configuration based on the minimal matching |
parameters. In particular, the Initiator and Responder each |
choose the minimum of: |
Own Other's |
Parameter Parameter |
WS WR <- Note the cross-comparison of |
WR WS <- these parameters. |
BS BS |
CM CM |
TL TL |
DR DR |
UR UR |
FI FI |
and the inclusive-or of the Quoting Sets. |
For example, if the Initiator sends the sequence: |
0x01 0x01 0x08 0x01 0x01 0x00 |
0x14 0xd4 0x00 0x00 <- Quoting Set |
0x00 0x00 0x00 0x00 <- |
0x01 0x00 0x00 <- DR UR FI |
and the Responder returns: |
0x00 0x01 0x04 0x00 0x01 0x00 |
18 |
0x54 0xd4 0x00 0x00 <- Quoting Set |
0x40 0x50 0x00 0x00 <- |
The following parameters are used by both entities: |
Parameter Initiator Responder |
WS 0x01 0x00 Initiator sends 1 |
packet ahead. |
WR 0x00 0x01 Responder sends 1 |
packet and waits for |
Postive Acknowledge |
BS 0x04 0x04 Both use 512 byte |
data body |
CM 0x00 0x00 Standard Checksum |
The following characters will be quoted when |
transmitted by either entity: |
0x01 0x03 0x05 0x10 0x11 0x13 0x15 0x81 0x91 0x93 |
SOH ETX ENQ DLE XON XOFF NAK SOH XON XOFF |
This would be the quoting used for a Responder |
having a modem which treats the 0x01 as "Escape to |
command mode" and in addition responds to flow |
control characters (0x11 0x13 0x91 0x93). |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.