Mike Montalvo wrote:

> I am using RS232 drivers/receivers to poll a 10X10 matrix of buttons.

  Can you clarify?  Does *every* remote (button sender) have a unique
line to the base?  What do you mean by "Matrix"?  Are you sharing RS-232
lines (paralleling)?

> each button is installed in an apartment up to 150 feet away.  They
> are all connected with 24 gauge twisted pair telco cable.

  Does this cable also carry the power, or is it locally supplied by,
e.g., a wall-wart?  Wall-warts have the advantage of isolating the
ground lines.

> I put 1 output bit high and check the 10 inputs one at a time.  Then
> I move on to the next output bit. I  scan all 100 switches about 3
> times a second.

  Does this imply that one transmitter at "base" sends to ten remotes in
parallel and each of these comes in to a separate receiver?

> I cant tell exactly how good it is because I'm constantly dealing with
> people ripping the buttons off the wall, grounding them out or
> connecting phone lines to them.

  ROTFL.  Sounds par for the course.  Are the offenders users or
tradesmen?
--
  Cheers,
        Paul B.