fredrick@acd.acd.ucar.edu (Tim Fredrick) (03/12/91)
There was some discussion about problems with modems a while ago but I missed out getting copies of what was said. I want to set up a fairly generic Hayes compatible modem to dial out with on my IBM Risc-System 6000/530. On the Pyramid, the same modem uses RS232 pins 2,3,7,8, and 20. The same configuration on the 6000 doesn't work for us. Using an RS232 tester, I see the lights on the AIX end for TD, RTS, and DTR. On the modem side, nothing. Can someone who has successfully set up a modem tell me what he did as far as wiring, configuring tty1 in smit, etc.? We're using the 8-port serial unit to connect to. Thanks in advance. --Tim
robin@pensoft.UUCP (Robin Wilson) (03/13/91)
In article <10556@ncar.ucar.edu> fredrick@acd.acd.ucar.edu (Tim Fredrick) writes: >set up a fairly generic Hayes compatible modem to dial out with on my >IBM Risc-System 6000/530. On the Pyramid, the same modem uses RS232 pins >2,3,7,8, and 20. The same configuration on the 6000 doesn't work for us. For configuring the wiring I can tell you IBMs official stand is that the only cable they support is the on they provide... However, that cable will wire the following pins: 1, 2, 3, 4, 5, 6, 7, 8, 20 And if you must drop one of these, I recommend "1" (in case you are using an RJ45 telephone wiring set-up). On the tty port side of things, just use "SMIT" to set up the port. If you want to use it as "dial-in" and "dial-out" you will need to set up the field "enable LOGIN" as "share" or "delay". BUT YOU SHOULD NOTE THAT SHARE AND DELAY ARE BOTH BROKEN UNTIL YOU APPLY THE 3003 UPDATE! The difference between share and delay (et. al.) reads as follows: SHARE - Starts a 'getty -u' on the tty. Getty waits for carrier before locking the port, and sending out a login herald. DELAY - Starts a 'getty -r' on the tty. Getty waits for a character on the serial input buffer before attempting to lock the port, and send out a login herald. ENABLE - Starts a 'getty' on the tty. Getty locks the tty immediately, and then waits for carrier to send out the login herald. (This can only be used for 'dial-in' or direct terminal connections.) DISABLE - No getty is started, can be used for 'dial-out' only. As you can see, the RS/6000 places a lot of credance in the state of of carrier for determining when to lock the tty and send out the login herald. This brings us to the modem setup... Most Hayes compatible (well, maybe not most... god knows there's a million brands of 'em) come with the same factory defaults as the original hayes modems. This means that carrier is set to "always on" by the modem. This also means that is you use the factory defaults, the modem will confuse the getty on the RS/6K. If carrier is strapped high, both "SHARE" and "ENABLE" work work functionally the same, lock the port, and send out a login herald right away. If the modem is set to "echo commands" this will cause all kinds of trouble... The getty will echo a herald, the modem will echo it back, the tty device will have echo turned on (when getty is started, the tty device is set to "echo") and will echo it back to the modem, the modem echos, tty echos, ad. infinitum. Obviously, the solution is to set carrier to follow true carrier on the modem. On the hayes "V-Series" modems this is accomplished by setting software switch "&C" to "&C1". The next important data about the modem setup is what to do when the RS/6K drops DTR. The RS/6K uses DTR to signal a "hangup" to the modem. This means that you must set the modem to use DTR in this manner, or the RS/6K will not be able to cause your modem to disconnect when the RS/6K needs it to. On the hayes "V-Series" modems, the software switch "&D" controls the modem's response to DTR signalling. I find that either "&D2" or "&D3" work best. Finally, you will need to make sure that you modem does not send any characters to the tty when people are attempting to dial-in, but before the carrier is up on the modem. Hayes modems will send a "RING" message to the tty device when someone in dialing into the modem. This "RING" message will confuse the getty on the port, because it will think that the user "RING" is attempting to login. You will usually get a failed login attempt, and possibly one of the "you used all upper case" login messages. So you need to be sure to set the quite mode software switch: on the "V-series" this is software register "Q". I find a setting of "Q2" (respond to local commands only) works just fine. I am sorry about the length of this posting, but so many people have asked for this information over-and-over again that I thought I would just post it all again.