Which is model KR optional sensor, NO (Normally Open, a contact) or NC (Normally Closed, b contact)?
The proximity sensor model listed in the catalog is NO (Normally Open, a contact). Three are attached. NO (Normally Open, a contact) sensor is delivered unless specified otherwise when you place your order. According to Wiring Methods, the photosensor can be switched between NO (a contact) and NC (b contact). ---------------------------------------------- Proximity Sensor NO (Normally Open, a contact): Output turns ON when the dog approaches. NC (Normally Closed, b contact): Output turns OFF when the dog approaches.