KEYENCE BL-180 - Manual (Page 18)

2.1 Read Operation
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2.1 Read Operation
2.1.1 Scanning method
There are two methods for triggering the BL-180 to read bar codes; the “Level sig-
nal” method and the “One-shot signal” method. The example given for these two
methods uses the “single label read mode” (see page 12), which reads one bar
code while trigger input turns on once, and uses the “after read” as the data-send
mode (see page 11).
Level signal trigger
When the trigger input turns on, LED emission begins and the the unit begins
reading. The LED turns off after reaching the specified decode count. Then, the
unit sends the readout data.
1. Set trigger input so that it stays on long enough for the LED beam to cover
the entire bar code.
2. After the trigger input exceeds the preset input time, the LED begins to emit.
3. The communication time can be obtained from the following expression:
4. The length of time that the OK/NG output is on can be changed to between
10 ms and 2.55 s.
5. The OK/NG output turns on 5 ms after the data has been read (or trigger
input turns off in case of reading failure).
Trigger input
Bar code
LED beams
Communication time
OK/NG output OK/NG NG
*2
*1
*3
*4
*5
Data bits + (1: If parity is used) + Start/stop bit
Baud rate
(code length of data to be sent + Header/
number of characters in delimeter) X