Omron F3SN-A Series Instruction Manual page 40

Output Waveform of the OSSD outputs
The OSSD outputs will be OFF as shown in the following figure in order to perform the OSSD circuit self-test
when the light curtain is in the ON-state. The OSSD circuit diagnosis is correct when this OFF signal is fed
back. If the output signal does not contain an OFF signal, the receiver determines that there is an output
circuit or wiring failure and goes into the lockout condition.
The number of OFF signals depends on the number of light curtains connected in series. (See the table
below.)
OSSD
In the same way, the OSSD outputs will be ON as shown in the following figure, to perform the OSSD circuit
self-test when the light curtain is in the OFF-state.
Check the input response time of a machine connected to the F3SN-A carefully to ensure the machine will
not malfunction due to the OFF signal.
OSSD
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Response time (ON to OFF)
ON
OFF
OFF signal
Approx. 25 µs
160 ~ 200 µs
Response time (ON to OFF)
ON
OFF
ON signal
Approx. 130 µs
When using 2 light curtains
No. of light
curtains connected
in series
No series
connection
2 light curtains
3 light curtains
When using 2 light curtains
No. of light
curtains connected
in series
No series
connection
2 light curtains
3 light curtains
Section 3 I/O Circuit
No. of OFF signals
within the response
time
1
2
3
No. of ON signals
within the response
time
1
2
3
B-33