Section 3 : Running a Server

Q310: [PC] Why can't I get HylaFAX to use RTS/CTS on a Digiboard port?

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Why can't I get FlexFAX to use RTS/CTS on a Digiboard port?

Has anyone got any experience of using FlexFAX with Digiboards and Hardware Flow Control ? Under System V.4?

Yes, I have it working with Dell SysVr4, an eisa Digiboard, and a recent Boca modem. Using the CCON/16 where the connector box doubles as an RS232 breakout box it is easy to see that h/w flow control is working. I understand that it might not work with other fax modems, though.

I've been using FlexFAX on a "normal" sas driven com port on Esix 4.0.4 with no problem. I expected to be able to simply switch it and the same modem over to a digiboard port. I use /dev/ttyi1a hard-linked to /dev/term/i1a. My problem is that I can't get the port to hold on to RTS/CTS flow control when using flexfax. Neither uucp nor ppp have any trouble with the Digiboard, but FlexFAX does. I can put hw flow control on the port with ditty, but as soon as FlexFAX runs its gone.

I have to admit I'm out of my depth with how the port knows what its supposed to be (I can read man pages, but that's not the same as knowing:-)). I've tried fiddling around with all sorts of things including ttymon, but had no luck so far.

Any tips would be most appreciated.

> Digiboard uses two device naming schemes with their drivers. > On SVR4, these are: > > /dev/term/i#x > and > /dev/term/i#X > Where: > "/dev/term/i" is the root name of all ports > "#" is the board number (ie. 1 for the first board, 2 for the second) > "x" or "X" is a letter a-z or A-Z (a for the first port, etc) > An upper case letter is used to denote the hardware flow control > port (or modem control port). This port blocks on open until > carrier is raised and enables RTS/CTS flow control. To use the > port without carrier, you need to open it with O_NDELAY set. > A lower case letter denotes a software flow control port that > does not need carrier for the open to succeed. The CX drivers use /dev/term/a##s and /dev/term/a##m where: a is a letter corresponding to which of the 16-port boxes you want ## is the port number (01-16) on that unit m indicates hardware modem control, s indicates software. > SVR4 added a an easy way to enable hardware flow control with the > termiox(7) extensions to termio(7), but some serial board makers haven't > seen the light yet. I thought these worked, but now it occurs to me that I have not had any occasion where I wanted to turn off h/w flow control if the connected device used it. > I have had to modify several programs to enable hardware flow control > for both SVR4 and Digiboard drivers. I wish I could just use the SVR4 > termiox(7) method. I've just used the modem control device in the first place and if necessary, modified the software to use O_NDELAY in the open(). In my opinion, software that talks to modems should be aware that carrier detect is not going to be present before dialing. > So, you could add some code to FlexFax to enable RTS/CTS flow control, > but it will only work for Digiboards or you can try to use the modem > control devices. FlexFAX will open the modem control device without any changes. However you may need to use the device without modem control for the faxaddmodem script and change the name afterwards. Version 5A of kermit has a "set carrier off" command so you can easily chat with off-line modems. I used it to send an "AT&C0&D0" command to the modem so it would temporarily hold carrier detect up for the faxaddmodem and probemodem scripts. I recommend keeping a copy around if you need a handy way to set up modems.

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