KPS101 keypads for use in older systems.

The classic KP1 Keypad from Audioaccess is recognized around the
world for its simplicity, reliability, and ease of use. In its latest revision, the
KPS101 contains a RS485 chip which allows for serial communications
back to the processor.
The KPS101 can be used “as is” with the
MRX, PX600, and PX700 systems. If upgrading
from either the MRX or PX600 systems to a
PX700 however, new keypads are needed as the
PX700 operates on a newer RS485 network. If
replacing a keypad in a MRX or PX600 system,
the KPS101 will work as is, since it is backwards
compatible.
If you have an older Audioaccess system, such as
the PX6 or PX4 the KPS101 will still work as a
replacement keypad, with some modification.
If you flip the KPS101 on its side notice there are a few layers stacked on
top of each other from the back of the buttons. The two outermost layers
are going to need to be removed, leaving the pins exposed to plug into the
ribbon cable used in the PX6 and PX4 systems.
Begin by taking off the nuts on the outside
cover.
Then cut the grounding wire below the next two levels, it is located next to
the pins.
Then unscrew the standoffs and gently pull
the middle layer off, being careful to not bend
any of the pins. Unscrew the second pair of
stand offs and replace them with the nuts
from the outer cover (removed first).
The finished product should look like this and
functions just like an original keypad.