Setting software flow control for modem on Digi Passport Console Server

We need to change some of the settings on the modem our Passport 16-port Integrated Console Server. The settings for the console ports need to stay the same. But we need to change the settings for the modem.

When I log(ssh) into the passport and look around, I see a couple of different things.

I can do a “ps -ef | grep modem”, and get the pid of the csm.modem process. When I do a cat of the process via /proc/[pid]/cmdline, I see that the csm.modem process was called as such:


One of the things I need to try is getting a software based flow control. That would mean flipping that “-f2” to a “-f1” (based upon /bin/csm.modem --help).

I also see the existence of /etc/ppp/options file, which would allow for the change of the crtcts setting to xonxoff.

How can I change these flags so that we can properly test the flow control?