Quote:
Originally Posted by Boozlefoot
My question is (realising the shorter the better) what are the maximum effective lead lengths for a DB25 cable in this instance? Has anyone had experience similar to this scenario?
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Hi Rod,
You need to qualify your question more.
Firstly, DB-25 refers to a type of connector, not a type of cable.
There are a range of cables types of different construction that can be used
with a DB-25.
Secondly, what type of signals are you carrying on the cable?
When you mention a CNC controller I suspect you might be using one that
relies on an old parallel port interface. Would that be true?
In which case, you might be referring to the 25-way DB-25 connector that
PC's used for their Centronics/IEEE 1284 parallel ports to interface
printers but which was also to interface to some equipment such as
CNC controllers.
Some of the later interfaces would commonly use ribbon cable.
The rule of thumb for the length of a Centronics cable was 6'.
However, people commonly used shielded cables for interfacing to
printers that were as long as 25'.
So if you are using a parallel port interface to a CNC controller, I'd
recommend 25' max if you were pressed. 10' would be in a more comfortable
zone and 6' is guaranteed.
If using unshielded ribbon cable, watch out for the fast rise times of the
signals that travel down which can give rise to massive amounts of EMI.
You don't want this to couple by cross-talk into your imaging gear.
In previous lifetimes I managed a group of engineers designing
laser printer controllers for major US and Japanese electronics
companies and personally designed and tested many parallel ports.
So if you are using a parallel port, I hope the above is useful to your
decision making.
Best Regards
Gary Kopff
Member IEEE 39 years
