Rockwell Automation 42CS Stainless Steel Photoelectric Sensors - Manual (Page 2)

2
Background Suppression Sensors
Target
Application Note
Due to the detection method, targets traveling horizontal to
the sensor’s optics are detected. Targets traveling vertically
may not be accurately detected. For reliable background
suppression, a minimum separation distance of 6 mm is
recommended between the target and the background.
Sensor Alignment
1. Pan the sensor left, right, up, and down to center the beam
on the sensed object (for diffuse), reflector (for polarized
retroreflective) or transmitter (for transmitted beam).
2. Fix the sensor position when the green LED is ON
(flashing) and the yellow output LED is ON (light sensed
and L.O. output energized). This set up assures a good
margin and that the signal received is greater than twice
the signal required to energize the L.O. output. The yellow
LED is on when the L.O. output is conducting.
Mounting the Sensor
IMPORTANT
Installing sensors on equipment running
above the indicated vibration and shock
specification may cause intermittent
operation.
Securely mount the sensor on a firm, stable surface or
support. A mounting which is subject to excessive vibration or
shock may cause intermittent operation. Mounting brackets
are available for a various installations. See accessories
section for an example.
Sensitivity Adjustment Modes
Two types of sensitivity adjustment modes are possible on the
42CS diffuse and polarized retroreflective: Standard Teach
and Precision Teach.
The Standard Teach is recommended for general purpose
detection of opaque targets, large objects or the absence of a
background that could interfere with the teach process. For
this teach process, the threshold levels are set at 50% of the
detected signal.
The Precision Teach is suited for the detection of small
targets or semi transparent objects, where a smaller variation
in gain needs to be sensed. For this teach process, the
threshold levels are set at below the hysteresis levels of the
detected signal.
Diffuse, Polarized Retroreflective and Clear Object
To teach the 42CS using the Standard Teach mode:
1. Place the target within the sensing range.
2. Enter teach mode by placing a ferromagnetic metal object
in the notch until the green LED flashes once. Note that the
green LED flashes while the teach process is active.
3. When the teach process is complete the green LED turns
solid ON. The yellow LED also turns solid ON when the
target is detected with at least twice the minimum amount
of light needed (Margin >= 2) for standard operation. A
flashing yellow LED indicates that the sensor operates with
a margin below the recommended 2X (1 < Margin < 2).
4. The sensor is now ready to operate (yellow LED is on
when the target is present)
To teach the 42CS using the Precision Teach mode:
1. Place the target within the sensing range.
2. Enter teach mode by placing a ferromagnetic metal object
in the notch until the green starts flashing. Note that the
green LED blinks multiple times while the teach process is
active.
3. When the teach process is complete the green LED turns
solid ON. The yellow LED also turns solid ON when the
target is detected with at least twice the minimum amount
of light needed (Margin >= 2) for standard operation. A
flashing yellow LED indicates that the sensor operates with
a margin below the recommended 2X (1 < Margin < 2).
4. The sensor is now ready to operate (yellow LED is on
when the target is present).
Background Suppression
To teach the 42CS background suppression:
1 Place the target within the sensing range.
2 Enter teach mode by placing a ferromagnetic object in the
notch until the green LED starts flashing. Note that the
green LED blinks multiple times while the teach process is
active.
3 When the teach process is complete the green LED turns
solid ON. The yellow LED also turns solid ON when the
target is detected.
4 The sensor is now ready to operate (yellow LED is on
when the target is present).
Teach Lock/Unlock
The 42CS teach is used to prevent unauthorized users from
changing teach settings and avoid interference from any
metal objects that could be in proximity of the teach notch
while in operation.
To lock the sensor:
Place a ferromagnetic metal object in the notch until the
green LED turns OFF. The sensor is now locked.
To unlock the sensor:
Place a ferromagnetic metal object in the notch until the
green LED turns ON. The sensor is now unlocked.