This can be attributed to any of the following:
* Bad serial cable (shorted, miswired, or a bad connector)
* Often gender changers, RJ45-DB25 connectors, and other adapters added to
the serial cable will sometimes create noise.
* Poorly sheilded cables and external noise source
* Power cables run pararell to serial cables. Its best to run serial
cables perpendicular to power cables. (Just like running speaker wire)
* External Noise source: old color TV's, arc welders, Mom's vaccuum
cleaner, low flying UFO's, etc.
* Modem: internal hardware failure, bad connector, improper power supply,
or just a bad design.
* Phone wire between modem and phone block. Be sure to use sheilded cable
here. Some people have telephone wires coming right out of the phone block
into an RJ11 plug into the modem, this is bad.
* Phone wire may be wired wrong, shorted or have loose or bad connectors.
* Phone block: watch for external noise sources, poor wiring jobs, loose
connections, crossed wires.
* Phone company: This is often the hardest to verify. In most cases you
can call the phone company and have them check for noise on specific lines.
* Framing errors can be caused if the serial cables are not firmly
connected. Likewise unplugging and replugging a serial cable while the
PortMaster is on will cause framing errors.
As others have pointed out the most effective way is to factor out each of
the above one at a time. Framing errors is hardware problems 99.9% of the
time. Hardware problems are diagnosed by swapping one thing at a time.
--- jstorms@livingston.com Diplomacy: The art of saying good doggie while seaching for a big rock.