Balluff BKT 21M-002 Serie Handbuch Seite 3

Photoelectric Sensors
Contrast Sensor BKT 21M-002-.-..
No. 830 513 E • Edition 0502
Contrast sensor
BKT 21M-002-P-S4 (PNP)
BKT 21M-002-N-S4 (NPN)
Advisory
The system is not permitted for use in applications
where personal safety depends on proper function
of the device.
The CE-Marking means that our products
conform to the requirements of the EC Guidelines
89/336/EWG (EMC) and the EMC Statute.
Testing in our EMC Laboratory, which is accredited by
DATech for Testing of Electromagnetic Compatibility, has
shown that these Balluff products satisfy the EMC
requirements of the following Generic Standards:
− EN 50 081-2 (Emission) and
− EN 50 082-2 (Noise Immunity)
Display and operating elements
Yellow LED
Output function indicator: The yellow LED is on when the
output is active.
Bi-color LED:
Stability and error indicator: The LED is green when the
sensor is ready and is working in a reliable range.
The LED flashes alternately red and green if the sensor is
improperly calibrated.
SET button: Holding down the button teaches the sensor.
This can also be accomplished using the Teach-in input.
The SET button is then disabled.
1 Output function indicator (yellow)
2 Stability and error indicator
(green/red)
3 SET push-button
Fig. 1: Display and operating elements
Connections
1 10...30 V DC
2 Teach-In (Connect to 0 V if not
used)
3 0 V
4 Output
Fig. 2: M12 connector
3
Installation
There are three ways to attach the sensor:
1. Using two screws (M4) and washers through the
housing mounting holes.
2. Using a mounting bracket (available separately).
3. Using special clamps (available separately) and the
dovetail housing profile.
The operating distance is measured from the front surface
of the sensor optics.
The M12 connector can be oriented at four different
ratchet positions of 0°, 90°, 180° or 270°.
Fig. 3: Dimensions
External Teach-In
The sensor can be calibrated using an external +V DC
signal on PIN 2 (Teach-in).
To do this, apply +V DC to the teach-in input before
powering up the sensor. This disables the SET button and
allows external calibration. A +V DC signal then has the
same function as pressing the button.
To restore button function, turn the sensor off, remove the
connection to +V DC (or apply 0V to the pin) and turn the
sensor back on.
Delay function
This function can be used to activate an off-delay of 20
ms.
1. Press the SET pushbutton and keep it pressed until the
bi-color LED turns off, blinks and turns off again. Now
release the button.
If the delay function is not active the green LED flashes
with 2 quick pulses over several cycles.
If the delay function is active the green LED flashes
with 4 quick pulses over several cycles.
2. To toggle the time delay (turn it on or off), press the
SET button once briefly. The new status is indicated by
the bi-color LED (see Step 1).