Re: K56 modem connection problems

John W Baxter (jwblist@olympus.net)
Sat, 9 Aug 1997 13:31:31 -0700

At 16:01 +0100 8/9/97, Richard Morrell wrote:
>I know this has been discussed in the list before, but I am having
>problems getting 56K modems to connect to my PM3. I am running a PM3 on 2
>PRI lines using ComOS 3.5c6 I had a user try to connect with a Rockwell
>56K modem and it wouldn't negotiate a lower speed. So I tried the init
>string that was posted here on the list (by jrowley@bitstorm.com -
>+ms11,1,14400,33600), but the modem would still not negotiate.

I've seen variations in the syntax for the +MS command.

For my SupraExpress 56e (on Mac), I hacked the Supra 288/336 connect
script something like this:

...
! Reset or return to command mode on DTR toggle (optional)
! JWB: S95=32 enables compression protocol result codes
! 8 enables ECC protocol result codes
! 4 enables rate information in the CONNECT reply
! 1 makes the rate information refer to DCE as desired
!
matchclr
matchstr 1 4 "OK\13\10"
matchstr 2 101 "ERROR\13\10"
!write "AT&F1E0&C1W1S7=120S0=0\13"
write "AT&F2E0&C1W1S0=0S95=45\13"
!write "AT&F2E0&C1W1S0=0S95=45\13+MS=V34,1,2400,33600\13"
matchread 30
inctries
iftries 3 101
!
! Reset the Modem on setup failure
!
DTRClear
pause 5
DTRSet
flush
jump 3
!
!
@LABEL 4
! JWB try forcing protocol/speed here
matchclr
matchstr 1 9 "OK\13\10"
!V.34, auto, min 2400, max 33600
write "AT+MS=V34,1,2400,33600\13"
matchread 30
jump 101
...

-------
Note the two commented-out INIT strings...the first was the original; the
third failed. I'm guessing that the failure resulted from OT/PPP slapping
something onto the end of the supplied string (perhaps M1 ???).

Rather that worry about it, I created a separate loop to send the +MS
command after the INIT string.

The error checking may not be right (all the CCL <Communications Control
Language> I know I learned from reading scripts)...but it didn't fail me
while I was using this script. [The last thing I did in CCL "improved"
connections using a different modem from 26,400 to 9600...that one has been
abandoned.]

The key here is the symbolic V34, rather than the numeric code 11. Check
the modem's manual to be sure what it wants.

--John

--
John Baxter (Born before ENIAC, but not by much.)
   jwblist@olympus.net      Port Ludlow, WA, USA