HP 3000 99x Family, Installation Manual

Page: 167 / 173

Appendix C C-17
Configuring the Remote Support Modem
Console/LAN Card-Modem Line Behavior
Console/LAN Card-Modem Line Behavior
CCITT Mode AP protocol 0
This protocol is known as HP-UX CCITT. The card waits for RI before raising DTR. It also
raises RTS when it raises DTR. If DSR does not come up within 25 seconds, DTR goes back
down. The connection also depends on CTS and DCD. DCD can drop for up to 400ms before
the connection will drop. CTS must stay high always. Once CTS drops, the connection
starts to drop. A new connection cannot occur until DSR, DCD and CTS all drop. FS can be
programmed to either state via the
CA
command.
Bell Mode AP protocol 1
This is sometimes called Bell simple protocol. It raises DTR when it can accept a
connection. The connection is valid when it sees DCD. It drives RTS whatever it was when
Remote is enabled (usually, RTS is low) and does not look at DSR or CTS. When a
disconnect is done, DCD must drop before a new connection can be made (i.e. it will not
raise DTR until DCD drops).
CCITT_BIS Mode AP protocol 2
This protocol is CCITT V.22bis. It requires the special cable A1703-63006 which is just like
the 92219Q cable with the exception that pin 9 on the computer end is routed to pin 12
(RS) rather than pin 22 (RI). DTR is raised whenever a connection is allowed. RTS follows
DSR. A connection is established when DSR is high. CTS can drop for an indefinite
amount of time without dropping the connection. The card will not send data to the modem
when CTS is low. DCD can drop for up to 400ms before the connection is dropped. Once the
connection is dropped, DSR, DCD and CTS must all go low before a new connection can be
made. RS controls what speed the card sends to the modem. If RS is high, the programmed
baud rate is used. If RS is low, half of the programmed baud rate is used. If you use the
92219Q cable, the baud rate will most certainly be half the programmed baud rate, since
RI will almost always be down. FS can be programmed to either state via the
CA
command.