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1. Note that this sensor will usually not work properly on HomeVision Port B Port B requires that an input be shorted to ground through less than 500 ohms resistance in order to read the input as low This sensor s resistance may only go as low as 10 000 ohms even when soaked in water Therefore the input will always be read as high even when wet Port C is a much more sensitive input and will go low even when the sensor s resistance only drops to 100 000 ohms Rain Sensor 1 Through a Powerflash Module The X 10 Powerflash module sends X 10 signals when the input to it closes By connecting the sensor to in you can avoid having to run wires to HomeVision However the X 10 signals may interfere with other X 10 signals The connection process is as follows e Use two wires to connect the sensor to the Powerflash module e Set the Powerflash module to the desired house code and unit code e Set the Powerflash module Mode switch to 1 e Set the Powerflash module Input switch to B Note that the Powerflash module is not as sensitive as HomeVision Port C If the sensor is only slightly wet the Powerflash module may not trip where Port C would PROGRAMMING NOTE This example assumes the sensor is connected directly to an input port not through a Powerflash module If you re using a Powerflash module then you would use the X 10 ON and OFF signals as inputs instead of the input ports There are several ways to use the sensor in yo2. HOMEVISION RAIN SENSOR This article describes how to interface the HomeVision Rain Sensor to the HomeVision controller SENSOR MOUNTING LOCATION The rain sensor must be mounted outside and located so rain can fall on it It you put it near a wall and the wind is blowing away from the wall it may not get wet Here are some possible locations The roof perhaps near an antenna or on top of a rain gutter On the top of a screen enclosure By the pool but where it won t get splashed on On or near a satellite dish The top of an outdoor air conditioning unit The mailbox A light post The top of a fence A flagpole At the bottom of a rain gutter downspout CONNECTING TO HOMEVISION You can connect the sensor directly to a digital input or through an X 10 Powerflash module A direct connection is the most reliable method and is recommended where practical Direct Connection Run two wires from the sensor to where HomeVision is located Connect them to HomeVision Port C and configure Port C as an input The connections are as follows 1 Connect one wire to the desired input terminal block inputs C 1 through C 8 2 Connect the other wire to ground terminal block C 10 To Port C input Sensor To Port C ground When the sensor is dry it will be electrically open This causes the input port to stay high its normal state When the sensor gets wet it s resistance decreases and the input port will go low to ground
3. en have HomeVision track how long it rains each day week or month and display the information on your TV The sensor can also be used as a water detector in a variety of situations such as Under a hot water heater to detect a leak In a basement to dectect flooding Under a washing maching to detect a leak or a broken hose Anyplace else water may leak Rain Sensor 3
4. es low the low actions are performed and the wait timer starts running After one minute the timer goes off and the flag is SET indicating it s raining When the rain stops and the sensor dries out the port goes high One minute later the wait timer times out and the flag is changed to CLEAR Thus the flag indicates whether or not it s raining but with a one minute delay e Now let s assume again that it s not raining and the flag is CLEAR The port then goes low but only for a few seconds When it first goes low the wait timer starts running waiting to set the flag Before the timer expires the input goes back high and the high actions are performed Since the same timer is used for both sets of actions this effectively cancels the first wait timer then restarts it waiting to clear the flag Thus the flag will never be set by the low actions since it s wait timer was cancelled After one minute the second wait timer expires and clears the flag Of course the flag was already clear so this has no real effect With this schedule changes in sensor state of less than one minute are effectively ignored If it s not clear why the wait timer works this way carefully read the timer chapter of the HomeVision user s manual CONCLUSION You can use the HomeVision rain sensor to know when it s raining adjust the sprinker watering schedule and close automated windows or skylights With some creative programming you can ev
5. ur schedule The most obvious is to check the input port with an If Then statement whenever you need to know if it s raining Another method is to use a flag to store the current state and set or clear it every time the input port changes However both of these methods have the drawback that the sensor may switch back and forth frequently if it s only slightly wet A better way is to use a flag to hold the current state but only change the flag after the input port has changed for a certain period of time For example you might change the state only if the input remains steady for one minute Here s an example of how to accomplish this 1 Create a flag named It s Raining 2 Create a timer named Timing Rain Sensor 3 In the Low Actions for the sensor input which are performed whenever the port goes low it stops raining enter Wait 1 minute with timer Timing Rain Sensor Then Set flag It s Raining End wait 4 In the High Actions for the sensor input which are performed whenever the port goes high enter Wait 1 minute with timer Timing Rain Sensor Then Clear flag It s Raining End wait 5 Whenever you need to know if it s raining check the state of the It s Raining flag SET means it s raining CLEAR means it s not Rain Sensor 2 Here s how this works e Assume it s not raining and the flag is CLEAR When the rain starts the port go
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