[ltp] IBM 600E, RH9, minicom problem

[James Knott]

Heiko Rosemann wrote:
> Hi,
> 
> On Fri, 27 Feb 2004, Bill Voight wrote:
> 
> 
>>Sports fans,
>>
>>IBM 600E, RH9, minicom serial port  Setup- /dev/ttyS0 9600 8N1, Hardware
>>flow control, no Software Flow Control
>>
>>I'm using settings identical to those I've been using on several other
>>RH boxes to connect to the A serial port of some U2's.  I am using a
>>known good null modem cable and gender bender to connect.  Works fine on
>>the desktops, no dice on the IBM 600e.  I've run the diags from the
>>600E's bios- they show everything's OK.  Have had no luck with docs- I
>>haven't found anything indicating there's anything different about the
>>serial port on a 600E.  Setserial output from both is listed below- it's
>>identical.  Anybody got any ideas?
> 
> 
> I recall there have been a few problems with laptops who do not deliver the
> standard +15V/-15V RS232-signals, but lower voltages (+7V/-7V is a number I
> seem to recall) So if you have some access to a scope, it might be worth
> measuring the voltages on the port pins. Most serial devices work with
> signals that low, but some refuse.

Given that the specs require a device to work with as low as 3V and high 
as 25V, it's the receiver that's substandard.