brian@tank.uchicago.edu (Brian Yanny) (11/09/89)
I'm trying to get two Suns (either OS3.5 or OS4.0.3) talking to each other at 38.4kbaud using two Microcom QX/V.32c data compression modems. The phone connection is at 9600 baud but the serial ports are at 38.4k to handle the compressed data. The Suns are set in "TANDEM | RAW" mode or "TANDEM|CBREAK". TANDEM is Suns/Unix's port setting which means "Watch the input buffer, when nearly full send a XOFF, then send a XON when empty". RAW means receive all characters as is, CBREAK receives all characters and will stop/start on XOFF/XON. The modems are set to bi-directional XON/XOFF flow control. The modems support hardware RTS/CTS flow control, but Sun OS3.5 does not and Sun OS4.0.3 only supports it in one direction. That is, if the modem drops the CTS line, the Sun stops sending, but there is no hardware flow control equivalent of "TANDEM", that is, you can't drop the RTS line when you input buffer gets too full. Thus I'm stuck using "TANDEM" (XON/XOFF) flow control. Sun doesn't offically support 38.4k, but they've got entries for it in their available speed tables, and I am able to get things to work "in one direction at a time". That is, one sun can send at 38.4 and the other will receive (and perform XON/XOFF) just fine. However, if I try to simultaneously send and receive things tend to lock up and eventually transmission stops. One can simultaneously send and receive "small" messages, of the order of 64 bytes. As soon as one sends more than a message or two of more than 64 (while a long transmission is going the other way), however, things stop. The messages were chosen to have no embedded XON/XOFF characters. Can anyone advise? Has anyone gotten anything similar to work? I have also tried this at 19.2k and 9600, same problem. At 4800 things seems to work, but that defeats the purpose of the high speed data-compression modems. brian yanny brian@oddjob.uchicago.edu University of Chicago
neil@cpd.com (Neil Gorsuch) (11/20/89)
In article <6205@tank.uchicago.edu> brian@tank.uchicago.edu (Brian Yanny) writes: >I'm trying to get two Suns (either OS3.5 or OS4.0.3) >talking to each other at 38.4kbaud using two Microcom QX/V.32c >data compression modems. The phone connection is at 9600 baud >but the serial ports are at 38.4k to handle the compressed >data. The Suns are set in "TANDEM | RAW" mode or "TANDEM|CBREAK". >TANDEM is Suns/Unix's port setting which means "Watch the input buffer, >when nearly full send a XOFF, then send a XON when empty". >RAW means receive all characters as is, >CBREAK receives all characters and will stop/start on XOFF/XON. >The modems are set to bi-directional XON/XOFF flow control. >The modems support hardware RTS/CTS flow control, but Sun OS3.5 >does not and Sun OS4.0.3 only supports it in one direction. >That is, if the modem drops the CTS line, the Sun stops sending, >but there is no hardware flow control equivalent of "TANDEM", that is, >you can't drop the RTS line when you input buffer gets too full. The following is a biased suggestion 8-). If you use our new serial/SCSI interface, you can use full RTS/CTS/DSR/DTR/XON/XOFF throttling in any combination while using the standard tty drivers supplied with the Sun's. Works with any SCSI equipped Sun. -- Neil Gorsuch INTERNET: neil@cpd.com UUCP: uunet!zardoz!neil MAIL: 1209 E. Warner, Santa Ana, CA, USA, 92705 PHONE: +1 714 546 1100 Uninet, a division of Custom Product Design, Inc. FAX: +1 714 546 3726 AKA: root, security-request, uuasc-request, postmaster, usenet, news