Path: utzoo!mnetor!uunet!husc6!bloom-beacon!gatech!hubcap!ncrcae!ncr-sd!sagpd1!banderso
From: banderso@sagpd1.UUCP (Bruce Anderson)
Newsgroups: comp.dcom.modems
Subject: US Robotics / Micom incompatibility
Message-ID: <267@sagpd1.UUCP>
Date: 7 May 88 08:15:06 GMT
Reply-To: banderso@sagpd1.UUCP (Bruce Anderson)
Distribution: na
Organization: Scientific Atlanta, Government Products Div, San Diego, CA
Lines: 31
Keywords: US Robotics, Micom

Recently, I had a requirement for an inexpensive 2400 bps modem so
I went out and purchased a US Robotics unit. This wasn't the Courier
model but the less expensive Sportster 2400.

For a couple of days I just used it with a terminal to work on a
remote host and it worked without a flaw. When that job was done I
connected it to our Micom port selector (model Instanet 6000) as a 
call out unit. In this configuration it worked fine at 1200 but at
2400 it couldn't receive more than about 10 characters in a row 
without starting to garbage some of them. I tried using a Prometheus
and an Anderson-Jacobson unit and they work perfectly under identical
circumstances.

Through trial and error, I discovered that if the remote host is set
to 2 stop bits rather than 1 stop bit, the problem goes away. It also
goes away if the connection through the Micom unit is started at 1200
and then upped to 2400. This causes the port selector to simply sample
each bit as it comes in rather than treating a byte as a single entity
as it does when you make the connection at 2400.

I've talked to both Micom and US Robotics and neither had any suggestions
or explanations to offer. (Actually the person I talked to at Micom
was not familiar with the port selector and gave me information which
I later found out was directly contradicted by the manual).

If anyone has an explanation for what might cause this I'd be interested
in hearing it. Otherwise, just be aware that there seems to be an
incompatibility between these two products.

    Bruce Anderson   -   Scientific Atlanta, GPD
    UUCP: ... ncr-sd!sagpd1!banderso