problems with serial port...

[Brad Pears]

I have a P3 machine with WinXp Pro installed. We are using a COMDIAL phone
system and I can dopwnload data from this system using a serial connection
between the two.

To connect, I use hyperterminal but am getting all kinds of hioergliphics...
I am connected at the proper baud rate (19,200) as I can read most of the
text. About every 10th charactor seems to be a "special" character. The
cable is only about 5 feet or less in length and I have also tried lowering
the baud rates - to no avail....

I tried using TTY as opposed to ANSI but no luck - same deal.

Originally I had this connected to an older Win98 machine - it was an old P1
machine with 32mb RAM and is now dead. It worked flawlessly with the exact
same COM port settings and TERMINAL settings...

Could this be a case of a different type of physical COM port causing the
problem?

Any help in this matter would be greatly appreciated!


Thanks,

Brad

 

[Guest]

Are you sure you don't need a null modem?

 

[Yves Leclerc]

What you seem to be getting is "static" accross the cable. You say the
COMDIAL system work with Win98SE but how "good" is the cable now? Can you
get a replacement cable?

 

[Brad Pears]

If it was a null modem issue, would I even get any communication at all??

Brad

 

[Brad Pears]

Yes, definately possible it's the cable - but how do you exxplain it working
perfectly on the old computer - using an older COM port - driver etc... and
not on the newer machines? That's why I'm wondering if it has something more
to do withthe phgysical serial port - or the drivers being used.... Since I
posted, I even tried a newer P3 machine with Win98 SE installed and had the
exact same issues with the serial port on it...

Brad

 

[Jeff Richards]

This could be caused by data overrun. One way to test this is to change the
baud rate (at both ends, obviously) and see if the problem changes. Overrun
can occur if the two systems are configured for different handshaking
(hardware vs XON/XOFF) or if they are configured for hardware handshaking
and the wiring doesn't support the handshake signals. You will also get odd
characters if one end is configured for XON/XOFF and the other end is
configured for hardware handshake, even if no overrun is occurring.

The physical arrangement of the serial ports would not be relevant to this
problem.

 

[Thomas Lutz]

Most likely the problem is a mismatch in the serial communications
parameters. For example, suppose that one end is set up to use 19200
Baud, No Parity and 8 Databits and the other workstation is set up to
use 19200 Baud, No Parity and 2 Stopbits.
Check that the parameters that you use match exactly.
If that does not cure the problem, check the cable connection for
wiring faults.