Connecting Two Pods Back-To-Back - HP 82718A Expansion Pod Reference Manual

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Software Usage and Examples
3) When finished dialing, the user must leave the phone off-hook or the call will be terminated. Then
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the user presses the key to signal the end of dialing. The program must then take the modem
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off-hook and monitor the line status using the 0 (ORIGINATE) command. The program would then
proceed as if it had dialed the number itself. The user can put the phone back on-hook any time
after the 0 command is executed.
This program gives an example of manual dialing. The
~'J.:=.
it. ••
message is needed because the H
command takes 3 s to hang up the modem.
1 (1 I t·tpUT
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t'l.:=.nu.:t 1 d i.:t I? 1::I.····n: "; A$
2~:1 IF UPPC$ Ui$::' =
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'y'
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THEt·~ :::0 EL~:;E BEEP I~ D I ~:;F'
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Done
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I~ ~:;TOP
:::(1 D I
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it. •••
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I~
t'10DOUT
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~·~h
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:~.:CHF::$
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F $=
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~·~OK
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I~
GOSUB 1
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Pt-e::":.s [PTt·~ ]
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Jhen done d i.31 in';.
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50 IF KEY$#CHR$(13::' THEN 50
60 t'10DOUT
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:~.:CHR$':: 1 :::::. I~ F$=
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~·~CCtl··H·~ECT
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I~ C;O~:;UB 1000
7(1 BEEP
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D I
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Connect. ed !
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I~ ~:;TOP
1000 2$=""
1010 2$=2$&MODIN$ @ IF
POS(2$~F$::'
THEN PETURN ELSE 1010
Connecting Two Pods Back-to-Back
The modem can be placed in either of two opposing modes of operation: ANSWER mode and ORIGINATE
mode. When the modem enters ANSWER mode, it goes off-hook, transmits an answer tone, and waits 20 s
for an originate tone. Conversely, when the modem enters ORIGINATE mode, it goes off-hook and
monitors the phone line for an answer tone for about SO s.
If one HP 82718A is in ANSWER mode and another is in ORIGINATE mode, the two modems can
communicate with each other directly. The only hardware necessary for this modem-to-modem
connection is a piece of telephone cable with a male modular connector on each end. By connecting the
two modems with the cable, placing one modem in ANSWER mode and the other in ORIGINATE mode, and
synchronizing them so that the answer tone and the originate tone occur concurrently, the communication
link is established.
Below are two programs, one for each of two HP 82 718As; the first one will put its modem into ANSWER
mode, and the second one will put its modem into ORIGINATE mode. The programs then monitor the
status of the modems to see when they are communicating with each other. The two programs need to be
run at approximately the same time, since the originating modem only has 20 s to detect the answer tone
issued by the answering modem.
The program for the answering modem is as follows:
10 ! This ModeM is set to ANSWEP Mode
20 MODEM ON ! Turn on ModeM
::;:0 t'10DOUT
II
~.~.:t
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:3.:CHP$':: 13::' ! Ent. et- At·~S~'JEF.:
Plode
40 IF NOT HOOK? THEN 40 ! Wait unt.il ModeM is off-hook
50 ON l+HOOK?+CAPRIEP? GOTO 60,50,70
6~:1 D I ~:;P
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tkl connect. i on
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I~ BEEP 22~J, 1 ~ STOP
7(1 D I SP
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Connect. i on est. .:tb 1 i shed
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80 MODOUT KEY$
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DISP MODIN$;
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GOTO 80
40