turgay-bas
Üye
- Katılım
- 29 Ağu 2010
- Mesajlar
- 1
- Puanları
- 1
- Yaş
- 34
4 e ayrılır kardeş istersen şimdi ben yazı yapıştırıcam çevir çvire bilirsen
he PNP sensor:- This is a sensor whose output pulls up to the positive supply rail when it senses a metal target. Thus any attached load to the sensor output must be connected between zero volts & the output of the sensor to operate.
This type of sensor is very vulnerable to short circuits to earth ( zero volts), a common fault if the wiring chafes/ becomes damaged. Often it will fry under this type of fault.
NPN sensor :- This is a sensor whose output pulls down to the negative ( 0 volts) supply rail when it senses a metal target. Thus any attached load to the sensor output must be connected between the Positive supply rail & the output of the sensor to operate. This type of sensor cannot survive a short up to the positive supply rail ( a very rare occurrence!). Shorts to the negative rail (zero volts) will not damage it at all & it can tolerate this indefinately.
Other factors affecting choice :- If there is a PLC attached then :-
a/ If the input device of the PLC registers a logic high/true state when left open circuit then this type of input is best served by an NPN sensor. This will pull the PLC input low when a target is sensed.
b/ If the input device of the PLC registers a logic low/false state when left open circuit, then this type of input is best served by a PNP sensor. This will pull the PLC input high when a target is sensed.
he PNP sensor:- This is a sensor whose output pulls up to the positive supply rail when it senses a metal target. Thus any attached load to the sensor output must be connected between zero volts & the output of the sensor to operate.
This type of sensor is very vulnerable to short circuits to earth ( zero volts), a common fault if the wiring chafes/ becomes damaged. Often it will fry under this type of fault.
NPN sensor :- This is a sensor whose output pulls down to the negative ( 0 volts) supply rail when it senses a metal target. Thus any attached load to the sensor output must be connected between the Positive supply rail & the output of the sensor to operate. This type of sensor cannot survive a short up to the positive supply rail ( a very rare occurrence!). Shorts to the negative rail (zero volts) will not damage it at all & it can tolerate this indefinately.
Other factors affecting choice :- If there is a PLC attached then :-
a/ If the input device of the PLC registers a logic high/true state when left open circuit then this type of input is best served by an NPN sensor. This will pull the PLC input low when a target is sensed.
b/ If the input device of the PLC registers a logic low/false state when left open circuit, then this type of input is best served by a PNP sensor. This will pull the PLC input high when a target is sensed.
)
