How to make a shielded serial cable

[Belinda Frick]

The following instructions should be followed to make a correctly shielded serial cable. This cable will ensure that interference is limited as far as possible.

If there is still corruption of data after this cable is used,the problem can be interference on the comports of the PC of the PABX itself.

Required:

• Metal DB connectors
• Shielded Serial cable

A shielded serial cable will have a foil wrapping around the wires.
There is also an earth wire included amongst the normal pairs.

The earth wire must be soldered to the metal DB on both sides of the cable. This will ensure a common earth is used.

With very strong interference there might still be problems.

CAT-5 is not a good option for use as serial cables since they are generally not shielded and there isn't any earth wire, but at some sites where there is little or no interference, it will work without problems.

Telephone wire should not be used as serial cable at all since it is very susceptible to interference.