12
3M™ MicroTouch™ Controller RX142 Reference Guide
3M Touch Systems, Inc. Proprietary Information
CAUTION
To avoid possible damage to the controller,
you must provide a path for electrostatic
discharge (ESD). The controller mounting hole near the sensor connector should be
used to connect to chassis safety ground and must be attached by the shortest possible
route to a good earth return (chassis) in all applications.
Note:
To avoid possible damage to one or both of the power supplies, do not supply
both internal power and external power to the controller. Power from two sources could
cause damage.
Using an Internal Power Supply to JP4
Provide power directly to the controller using JP4 (AMP 640457-3). Use a mating 3-pin
connector (AMP 3-640469-3 or equivalent) and connect Pin 1 to 5VDC power and Pin 2
to the return or (alternately) 12VDC to Pin 3 and Pin 2 to the return.
Using an Internal Power Supply with a Custom Serial Cable Design
When creating a custom serial cable connection, you can provide power to the controller
through the mating Molex connector. Refer to Table 1 for more information on actual
cable connections. Unlike using JP4 to supply power, you can only use 5VDC at the
serial interface.
1.
Obtain an 8-pin Molex connector 51004-0800.
2.
Attach power and ground to the connector, (Pin 6: +5V, Pin 7: Ground).
Mounting the Sensor
The RX142 controller will work with sensors that meet the following specifications. The
sensor may work beyond these limits but with reduced performance.
Minimum
Maximum
Capacitance top sheet to substrate
None
70nF
Resistance corner to corner or side to side
100 Ohm
500 Ohm
Resistance top sheet
100 Ohm
5k Ohm
It is critical for you to understand the tail orientation of your sensor prior to connecting
the controller. This will affect how the controller interprets your touch on the sensor.
Refer to the Chapter on controller communications for additional details.
Sensor Cable Connector
The sensor cable has a 4-pin single row locking female connector that plugs into the
controller. The controller is compatible with the “XYXY” latched connector pinout, not
the “”XXYY” style, non-latched connector pinout. Here, X or Y refers to one or the other
sheet, and + or – refers one or the other side of a sheet. The calibration process sorts out
left/right and up/down.
Connector pins 1 and 3 must be connected to one sheet and pins 2 and 4 must be
connected to the other sheet.
