Length Measurement - Omron CJ1W-CT021 Operation Manual

Length Measurement

6-2

Length Measurement

Application Description
Pusher
Conveyor belt 2
Encoder ( E2)
Covered configuration items in this example:
• Circular Counter
• Range Mode, setting Range Data
• Programmable Output Pulses (Output Pulse Duration)
• Digital Input Function (Functions 5 and 11)
• Capturing and reading Captured Values
• Logically AND-ing Output Patterns
In this example the length of objects is measured. Improper sized objects are
removed from the line by activating the pusher for one second. The measured
length of improper sized objects is stored in EM of the PLC as a 32-bits Counter
Value. The High-speed Counter Unit is DM-configured and works stand-alone
except for storing the size of improper sized objects in EM; a short ladder program
is written to read and store the length of improper sized objects into the CJ-series
CPU Unit. The Unit is in Range Mode.
Two incremental encoders are used. Encoder 1 is connected to Counter 1 and
encoder 2 is connected to Counter 2. By using two encoders the system also
takes into account alterations in the speed of conveyor belt 1 and 2.
Encoder 1 is connected to the shaft of motor 1. The length of an object on con-
veyor belt 1 is proportional to the number of pulses that encoder 1 generates. As
an object passes photo-electric sensor D1, Counter 1 starts counting pulses. If the
number of pulses counted is within one of the predefined invalid ranges (i.e. the
length of the object is too small or too big), the object has to be removed from the
line by the pusher.
In order to activate the pusher at the right moment (i.e. the object with incorrect
length is in front of the pusher) encoder 2 and photo-electric sensor D2 are used.
When the end of the object leaves the beam of photo-electric sensor D2, Counter
2 is reset and continues counting. The pusher will be activated for one second as
soon as the object is in the predefined range of Counter 2.
Photo-electric
sensor ( D2)
Motor 2
Photo-electric
sensor ( D1)
Conveyor belt 1
Section 6-2
CT041
RUN ER C ERH
CH1 A B Z I0 O0
CH2 A B Z I1 O1
CH3 A B Z I2 O2
CH4 A B Z I3 O3
MA CH
No.
X10 1 X10 0
1 1
CN2 CN1
20 20
AB AB
Motor 1
Encoder ( E1)
PS204S
Power
149