Omron CS1W-CT021, Operation Manual

Page: 171 / 201

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Section 6-2
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To measure the length of objects the pulses of encoder E1 are counted by Circular
Counter 1 (corresponding DIP switch at the back of the rear panel is in the ON-
position). Photo-electric sensor D1 is connected to Digital Input I0. Digital Input I0
controls Counter 1 and is assigned Digital Input Function 11 (Reset, Stop, Capture
and Continue).
Digital Input Function 11
At the falling edge of Digital Input I0, when an object enters the beam of the photo-
electric sensor, the Counter Value is reset, the gate is opened and Counter 1
starts counting pulses from zero. At the rising edge of Digital Input I0, when the
object leaves the beam of the photo-electric sensor, the Counter Value of Counter
1 is captured and the gate is closed.
Reading Captured Value By issuing an IORD-instruction from the PLC ladder program the captured Coun-
ter Value is read. The length of improper sized objects is stored in Extended Mem-
ory of the PLC (refer to the ladder program example on the next pages).
Measuring length The length is measured by Counter 1 and should be ideally 5000. The valid range
for the length of an object is 4900 – 5100. If the length of an object is in Range 0
(4000 – 4900) or Range 1 (5100 – 6000) the object is improperly sized and must
be removed. Digital Output O0, in the Output Pattern of Counter 1, is turned ON
when the Counter Value is within Range 0 or 1.
Removing objects Timing the correct moment to remove an object for the pusher is done by the com-
bination of encoder 2 and photo-electric sensor D2. Objects are removed by the
pusher which is located at conveyor belt 2. Photo-electric sensor D2 is connected
to Digital Input I1. Digital Input I1 controls Counter 2 and is assigned Digital Input
Function 5 (Reset Rising Edge).
Gate Open
Gate Closed Gate Closed
Gate Open
Capture Capture Capture
Object passes
photo-electric sensor
Object pas ses
photo-electric sensor
Reset Reset
5000 4000 4900 5100 6000
Range 0 Range 1
Counting Range
Circular Counter 1
Digital Output O0 ON
W902-E2-03.book Seite 156 Donnerstag, 7. Oktober 2004 2:06 14