G'day everyone,
I was wondering whether I can use an RFID reader as a power-on/off switch in a hotel room? To turn the power on you would have to place the RFID card (which is also the room key) on the reader. This would allow to turn off the power when you leave the room and take the key with you. Do you think it is doable? I mean the thing I'm worried about is how RFID readers work when you place a card on them or hold the card in front of them for a longer time? I know that when you pass the card in front of the reader it reads the data and puts it in a bufor which can be read through RS232/485 or some other standard. But what happens when you hold the card after it has been read? Does it read it again when you empty the bufor? or does it work like a rising edge, so reads the data from the card when the card is near and doesn't do anything until you take the card away and past it in front of the reader again? if it allows a continuous reading mode it's quite easy to create a simple power-on/off button, because all you need is to check the bufor every 5-10minutes and if it's full (and has the right IDnumber) it's all ok.
By the way it's really hard to create a simple yet effective system that turns the room power on/off. I thought of different things like room occupancy sensors (PIR motion sensors), counting guests with photorelays installed near the door or simply turning the power off when you lock the door from the outside with your card. Unfortunatelly all of those mechanisms doesn't really work when you leave someone in the room and lock the door from the outside. The person left in the room might be a sleep and so motion sensors won't work and the power will be turned off. Photoreleays might have trouble counting people that come in or go out when two people pass in the doorway. This miscalculation might lead to a situation when some one is still inside and the power is being turned off.
Perhaps some of you has some ideas on how to solve this problem? The only thing I can think of is using motion sensors + the fact of closing the door from the outside. If you close the door using the RFID reader outside, the motion sensor checks whether there's movement inside the room in the following 10-20min. If there's any movement the power is not being turned off and only the door stays locked. If no movement is detected the power is turned off, but the motion sensor stays active. If it detects movement after the power turn off it will turn it back on, as this means someone probably stayed inside.
Cheers and thanks in advance,
Tom
I was wondering whether I can use an RFID reader as a power-on/off switch in a hotel room? To turn the power on you would have to place the RFID card (which is also the room key) on the reader. This would allow to turn off the power when you leave the room and take the key with you. Do you think it is doable? I mean the thing I'm worried about is how RFID readers work when you place a card on them or hold the card in front of them for a longer time? I know that when you pass the card in front of the reader it reads the data and puts it in a bufor which can be read through RS232/485 or some other standard. But what happens when you hold the card after it has been read? Does it read it again when you empty the bufor? or does it work like a rising edge, so reads the data from the card when the card is near and doesn't do anything until you take the card away and past it in front of the reader again? if it allows a continuous reading mode it's quite easy to create a simple power-on/off button, because all you need is to check the bufor every 5-10minutes and if it's full (and has the right IDnumber) it's all ok.
By the way it's really hard to create a simple yet effective system that turns the room power on/off. I thought of different things like room occupancy sensors (PIR motion sensors), counting guests with photorelays installed near the door or simply turning the power off when you lock the door from the outside with your card. Unfortunatelly all of those mechanisms doesn't really work when you leave someone in the room and lock the door from the outside. The person left in the room might be a sleep and so motion sensors won't work and the power will be turned off. Photoreleays might have trouble counting people that come in or go out when two people pass in the doorway. This miscalculation might lead to a situation when some one is still inside and the power is being turned off.
Perhaps some of you has some ideas on how to solve this problem? The only thing I can think of is using motion sensors + the fact of closing the door from the outside. If you close the door using the RFID reader outside, the motion sensor checks whether there's movement inside the room in the following 10-20min. If there's any movement the power is not being turned off and only the door stays locked. If no movement is detected the power is turned off, but the motion sensor stays active. If it detects movement after the power turn off it will turn it back on, as this means someone probably stayed inside.
Cheers and thanks in advance,
Tom
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