Panasonic FP7 User Manual page 33

 Precaution when using LED-equipped lead switch
When a LED is connected in series to an input contact such as LED-equipped lead switch,
make sure that the on voltage applied to the PLC input terminal is greater than 21.6V DC. In
particular, take care when connecting a number of switches in series.
LED
LED
ON voltage
lead
contact
or above
switch
Power supply for input
 Precaution when using two-wire type sensor
If the input of PLC does not turn off because of leakage current from the two-wire type sensor
"photoelectric sensor or proximity sensor", the use of a bleeder resistor is recommended, as
shown below.
Two-wire
sensor
 Precaution when using LED-equipped limit switch
If the input of PLC does not turn off because of leakage current from the LED-equipped limit
switch, the use of a bleeder resistor is recommended, as shown on the left.
LED
lead
switch ｒ
Input
PLC
COM
＋
Input
Bleeder
Ｒ
resistor
COM
＋
Input
Bleeder
Ｒ
resistor
COM
＋
Power supply for input
3.2 Wiring of Input and Output
PLC
PLC
3-9