The module features:1. imported normally open reed2.the comparator output signals clean, good waveform, driving ability, than 15mA.3.the working voltage of 3.3V-5V4.the output form: digital switching output (0 and 1)5. a fixed bolt hole for easy installation6.small PCB board size: 3.2cm x 1.4cm7.using a wide voltage comparator LM393InstructionsReed is dry reed short, is a kind of passive electronic switch contact element has a simple structure, small size and easy to control, etc., the shell is generally a sealed glass tubes are installed there are two flexible iron reed panels, also called metal rhodium has a filling of inert gas. Normally, two glass tubes made of special materials reeds are separated. When a magnetic substance near the glass tube, under the action of magnetic field lines, the two reed pipe is magnetized and attract each other contacts, the reed will pull together to make a circuit of the connected node communication. After the disappearance of the external magnetic force, two reeds separately because of their elasticity, the line also disconnected. Therefore, as a signal to control the use of magnetic field lines switching devices, the reed can be used as a sensor for counting, spacing, and so on (in the security system is mainly used for door sensor, window magnetic production), but also It is widely used in a variety of communication devices. In practice, usually with a permanent magnet control the two metal sheets turned on or not, it is also known as "magnetron."The wiring diagram:

Source code:Aduino test program for DO connection (for example) :Aduino test program for DO connection (for example) :Int Led = 13; / / define LED interfaceInt buttonpin = 3; / / define the Reed sensor interfaceInt val. / / define digital variable valVoid setup (){PinMode (Led, the OUTPUT); / / define the LED for the output interfacePinMode (buttonpin, INPUT); / / define Reed sensor as the input interface}Void loop (){Val = digitalRead (buttonpin); / / to assign the value of digital interface 3 read valIf (val = = LOW) / / when the Reed sensor have a signal, the LED light{DigitalWrite (Led, HIGH);}The else{DigitalWrite (Led, LOW);}}}If (RI){The date = SBUF; / / microcontroller to acceptSBUF = date; / / microcontroller sendRI = 0;