KEYENCE SR-750 Series - Manual (Page 27)

27 E SR-750 UM
Point When a code is read at an interval shorter than the specified
output ON time, the OK/NG/ERROR output turns off even if the
output ON time of the previous output signal has not elapsed, and
a new output signal turns on for the specified output ON time. If
output terminal operations of the same type occur successively
(such as OK
→OK), the previous output signal turns off for 10 ms,
and then the new output signal turns on.
Refer to
"Page 15 Function and Operation of the Output
Terminals (OUT1, OUT2 and OUT3)".
Reference
The TRG BUSY output turns on from the time the trigger input turns on
to the time the code reading is complete or the trigger input is turned
off.
One-shot trigger
When the SR-750 Series detects that the trigger input is on, it turns on the lighting
for the specified one-shot trigger duration to scan a code.
When a code is read successfully, it stops illumination and sends the data. Other
operations are the same as those for the level trigger.
Use the one-shot trigger if the ON time of the trigger input is extremely short or if
you want to fix the read time.
„ Timing Chart
• When the trigger input stays on for the specified input time constant, the
illumination of the SR-750 Series turns on and the scanning begins.
When the reading is complete, the illumination stops.
• The input time constant for the trigger input can be changed to 1 ms, 2 ms, or 10
ms.
• The one-shot trigger duration can be changed within the range of 100 to 25500
ms.
• If the SR-750 Series fails to read a code within the one-shot trigger duration, it
stops illumination and outputs a reading error.
• Other operations and precautions are the same as those for the level trigger.
Point The ON state of the trigger input is recognized after the input stays
on for at least the specified input time constant.
The OFF state of the trigger input is recognized after the input
stays off for at least the specified input time constant.
Consequently, when the line speed is fast and fast pulse signals
are used as trigger input signals, be careful to make the ON/OFF
time of the pulse signals longer than the specified input time
constant.
Trigger input time constant = when a, if a becomes larger than b,
the OFF state of the trigger input is not recognized.
When a ≤ b, the ON/OFF state of the timing signal can be
recognized.
OK/NG ERROR
Trigger input
Code
Scanning + decoding
Data communication
TRG BUSY output
(When reading is successful) (When reading failed)
One-shot trigger duration One-shot trigger duration
OK/NG/ERROR output
Trigger input
a
b
4-3
Data Transmission Timing
This section describes the data transmission timing of the SR-750 Series.
Type of data transmission timing
The SR-750 Series offers the following 2 options for outputting the read data and
OK/NG/ERROR signals:
• Send after reading
• Send after timing OFF
Select the appropriate type for your application.
* For the sake of simplicity, Input time constant + Scan delay time is not shown in
the timing chart.
Send after reading
The SR-750 Series outputs read data and an OK/NG signal as soon as it
completes reading codes. If the SR-750 Series fails to read a code, it outputs a
read error code and an ERROR signal at the point when the timing signal turns off.
The timing charts are the same as those shown in "Timing Mode".
"4-2 Timing Mode (Page 26)"
Send after timing OFF
When "Send after timing OFF" is selected, the SR-750 Series outputs read data
and an OK/NG/ERROR signal at the next timing point for the specified trigger type.
Use this type to output data and output signals with the same timing.
„ Timing Chart for the level trigger
When the trigger input turns off, read data and OK/NG/ERROR signal are output.
• When a code is read successfully, the read operation stops.
• The TRG BUSY output continues until the trigger input turns off.
„ Timing Chart for the one-shot trigger
When the specified one-shot trigger duration elapses, the read data and OK/NG/
ERROR signal are output.
• When a code is read successfully, the read operation stops.
• The TRG BUSY output continues until the one-shot trigger duration elapses.
OK/NG ERROR
Trigger input
Code
Scanning + decoding
Data communication
TRG BUSY output
(When reading is successful) (When reading failed)
OK/NG/ERROR output
OK/NG ERROR
Trigger input
Code
Scanning + decoding
Data communication
TRG BUSY output
(When reading is successful) (When reading failed)
One-shot trigger duration One-shot trigger duration
OK/NG/ERROR output