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Thread: RFID access control

  1. #1
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    Question RFID access control

    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

  2. #2
    Moderator toscal's Avatar
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    Have a look at iButtons. http://www.myrialog.com/cgi-bin/ic/h...ml?id=vrjUpTjX

    Also try a goolge for iButtons.
    Good luck.

  3. #3

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    One hotel I stayed in had something similar.

    A slot that you placed the room key into (plastic card) and all it did was operate a microswitch to turn the power on.

    You could fool it by placing any plastic card eg loyalty card, credit card etc in there if someone needed to go out with the "key" whilst leaving someone in the room.
    KAT5.tv - affordable high quality AV Distribution
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    I have found the site I was originally looking for. www.iautomate.com/rfid.html
    Though one thing you have to be careful of is picking up stray RFID signals from other tags, such as when a resident from another room walks pass somebody else's door, it could trigger an occupied response. Though if the room is empty its not really a big deal, other than wasting electricity.
    I think the iButton solution might be a better bet as they need to be within 0.5cm of the reader. This product was what I had in mind when I thought about the iButtons http://www.myrialog.com/cgi-bin/ic/h...p/hc00041.html
    And when used with this could be a good starting point www.cc-concepts.com/products/ilock/

    Hope this helps.
    Last edited by toscal; 19th August 2007 at 07:54 PM.

  5. #5
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    Default re

    G'day,

    katman: yup there's a microswitch inside, so you can put almost anything in and the light will stay on for as long as you want. So that solution pretty much sucks

    thanks for the answers. Finally I decided to use motion sensors and the fact that the door was closed for the outside. After the door is closed the system checks if there's any motion within 30min and turns of the power. If someone is left inside, for example sleeping and not moving for 30min since the door was closed the power will go off, but as soon as the person moves it will be turned back on. I think it's not so bad and it's quite cheap.

    Other thing I was worried about is the security issue of proximity cards. I know they can be copied, using a simple reader and some software, but I'm not sure if I should worry about it. All the numbers used in the system are stored in a database and if someone looses a card and reports it, the card is being automatically removed form the system. Also if you return you card in the reception, for example when you go on a longer journey and don't want to take it with you, it's also being disactivated. So do you think I should worry about it?

    toscal: I know that iButtons are safer, but unfortunately PLC used in my system doesn't support 1-wire and there are no 1-wire -> Modbus converters. Also 125kHZ RFID tags must be in around 10cm to be read, so picking up signals from a different card is not a problem.

    Cheers,
    dsc.

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    Default Help on RFID room power control

    Hi guys, found this forum last night and reading with interest... My other half thinks I am mad and there is no one as geeky as me, how wrong she is!

    Hoped i could save you some time by commenting on this subject. You asked many questions, just hope you find the answers helpful?

    Quote Originally Posted by dsc View Post
    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?
    A. Systems like this exsist in many hotels, but just use a micro switch and yes, you can use any card.
    I have also come across and made a system that used a magnet. (use a Readswitch or a hall effect sensor)
    You could drill a binary coding in the card, or covertly create one within the card and use IR Sensors to look through it. (Just a idea!)
    I used to love making door access systems and alarms when I was a kidd. (I mean younger, still a kidd!).

    Quote Originally Posted by dsc View Post
    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.
    A. I does depents on what RFID Reader you are using, Normaly, the uP or uC is commanding the reader, the buffer is only aiding comms timing. So it is down to you to instruct the reader(Poll) for more or repeat information. so Yes Just keep polling for the Id.
    Most readers will issue a command when the card moves out of range. (Depends on the reader and config.)

    Quote Originally Posted by dsc View Post
    By the way it's really hard to create a simple yet effective system that turns the room power on/off.
    A. Why? You have :- PIR, Ultrasonic, Microwave and Thermopile to choose from. I work in a Hightech building, it has dualtech PIR/Ultrasound sensors about ever 15 Feet in the ceiling. They are very sensitive. Every sensor is networked into the building management system. Not only does it control the 6 (approx) lights around you, it controls on the HVAC and Security.

    Quote Originally Posted by dsc View Post
    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.
    A. One reasonably reliable system is to install an alarm, most people will set an alarm when no one is left in the room.

    Quote Originally Posted by dsc View Post
    The person left in the room might be a sleep and so motion sensors won't work and the power will be turned off.
    Q&A. Not quite sure what extent you want to turn things on and off? Quess? its lights, TV and Aircon in a hotel room. You do not want to kill room power when you are in it! Even when asleep, the last thing you want is the lights coming on every time you turn over in bed. Or the Aircon turning off in the middle of a heatwave(Not in the UK, I might add!). Also remember, people charge phones, digital cameras, camcorders and shavers during the night. Many hotels have a fridge, these run on a diffrent circuit that does not get cut.(But you pay to use it!)

    Quote Originally Posted by dsc View Post
    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.
    A. I Built a in / out counting system for a Year 9 (Yes, back in 1989 ish) Project using a BBC Micro, Counted people in and out of a lift.(Very hard to keep the count right!) Ended up with -4 people in the lift!!

    Quote Originally Posted by dsc View Post
    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,
    A. Out of the 50+ Hotels i have stayed in, not one has ever used the card to lock the door. You just close it behind you.

    Quote Originally Posted by dsc View Post
    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.
    A. This system is flawed, one many occassions, My misses or I, will leave the hotel room while the other is a sleep and dont forget the aircon / charging issues. Even the lights in my high tech building go out on me when I am working late. I end up pinning a piece of paper to the ceilin and pointing a desk fan at it(System circumvented!), works a treat.

    It seems like you are trying to fix a problem with a high tech solution that was solved 20 years ago with a plastic card and a microswitch. A have to ask, what is the actual problem you are trying to solve and why?

    Quote Originally Posted by toscal View Post
    Though one thing you have to be careful of is picking up stray RFID signals from other tags, such as when a resident from another room walks pass somebody else's door, it could trigger an occupied response.
    A. This depends on the RFID system you choose and card reader design. Check out NXP (Philips) Mifare RFID Cards. A passive system will have a read distance of 100mm aprx. You can design your read coil to only work within 2-10mm if you wish.

    http://www.nxp.com/#/homepage/cb=[ty...41863]|[4]
    http://www.nxp.com/acrobat_download/...on/m001052.pdf
    http://www.nxp.com/acrobat_download/...on/M067220.pdf


    Quote Originally Posted by toscal View Post
    Though if the room is empty its not really a big deal, other than wasting electricity.
    I think the iButton solution might be a better bet as they need to be within 0.5cm of the reader.
    A. An iButton is a "Contact device" using the 1-wire protocol. (Two connections really!!, Gnd and Data)

    Quote Originally Posted by toscal View Post
    This product was what I had in mind when I thought about the iButtons www.myrialog.com/cgi-bin/ic/h...p/hc00041.html
    And when used with this could be a good starting point
    www.cc-concepts.com/products/ilock/
    A. iButton / 1 Wire device

    Check this out: http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2829

    You can connect it to a serial, usb, parallel port using one of these:- http://para.maxim-ic.com/cache/en/results/4002.html
    or make a home brew:- http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2923

    Even sofware to play with it!:- http://www.maxim-ic.com/products/ibu...re/wirekit.cfm

    Includes an API as well.

    And its free!!

    Hope some of this is helpful...

    Whoops.. Run out of words.. to be cont..

    Ian - M1ANH
    Last edited by m1anh; 25th August 2007 at 10:27 PM.

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    Default Help on RFID room power control - Cont..

    Sorry, new to posting, got the thread in the wrong place!.

    Cont..

    Quote Originally Posted by dsc View Post
    katman: yup there's a microswitch inside, so you can put almost anything in and the light will stay on for as long as you want. So that solution pretty much sucks
    A. I think thats a little unfair!, If it sucks that bad, why is it used so much and not been changed it 20+ years. I saves 100's of megawatts every year, yes a slot with a microswitch in it.

    A. It does not need to be complicated, Just cheap, simple, maintainable and trouble free. yes, you can circumvent it, but thats because we are geeks!, we understand how it works, 95% of people don't!. It about social compliance. You are told there is a slot in you room that you put the card in, so thats what you do, straight after using the card to unlock the door. The slot serves a second very important purpose, it reminds you to take your door card with you!

    Quote Originally Posted by dsc View Post
    thanks for the answers. Finally I decided to use motion sensors and the fact that the door was closed for the outside. After the door is closed the system checks if there's any motion within 30min and turns of the power. If someone is left inside, for example sleeping and not moving for 30min since the door was closed the power will go off, but as soon as the person moves it will be turned back on. I think it's not so bad and it's quite cheap.
    A. A microswitch in a plastic slot is much cheaper!.

    Quote Originally Posted by dsc View Post
    Other thing I was worried about is the security issue of proximity cards. I know they can be copied, using a simple reader and some software, but I'm not sure if I should worry about it.
    A. RFID's on there own can be scanned and cloned while still in somebodys pocket. So you need to look into the challange and responce system that exists within the card, along side the secure data areas. You will NOT copy a MiFare Card! easily or maybe at all!

    Quote Originally Posted by dsc View Post
    All the numbers used in the system are stored in a database and if someone looses a card and reports it, the card is being automatically removed form the system. Also if you return you card in the reception, for example when you go on a longer journey and don't want to take it with you, it's also being disactivated. So do you think I should worry about it?
    A. Door Access cards in large hotels while administered by a computer are not in ANY way connected(RF or Wired) to the doorlocks on the rooms. All the data needed to control the lock is stored on the access card its self. If you lose the card, a new card is issued and it cancels the lost one(s). If you wants to know more, let me know.

    Quote Originally Posted by dsc View Post
    toscal: I know that iButtons are safer, but unfortunately PLC used in my system doesn't support 1-wire and there are no 1-wire -> Modbus converters. Also 125kHZ RFID tags must be in around 10cm to be read, so picking up signals from a different card is not a problem.
    A. I am not sure about MODBUS, never used it, however, if your PLC has a serial port and you have full control over it, you could use the

    DS2480 to bridge the gap between the PLC and 1-Wire.

    Hope some of this is helpful...

    Ian - M1ANH

  8. #8
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    What type of PLC are you using. If it can except some sort of input, either voltage or switched, then you can use iButtons. The circuit board from cc concepts is designed to operate a door strike relay. So just connect this to an input on the PLC if you can. And I know its probably not as easy as just connecting a few wires etc. It all really depends on the PLC you are using.
    The comments from m1anh about easily cloning an RFID card are quite valid. If you have a long range reader then its quite possible to sit in the hotel lobby and start cloning the cards. in people´s pockets. I've been involved in some basic RFID testing for asset tracking, and depending on the reader we could pick up RFID tags about 5 to 10 metres away.
    At the end of the day any system can eventually be circumvented. But the reason many hotels use plastic cards is that the cards are cheap to buy, can be used to store things like credit card info, name, address and of course room number etc. And work very well.
    I've been in some hotels where the only card that works in the slot is the room key. I normally use one of my frequent flyer cards, but in a couple of hotels this no longer worked, had to be the room key.
    Have a look at cyber keys from videx. www.videx.com these are virtually impossible to clone. Not only do you need to have the software, but then the passwords to then copy a key. You can also give each key a time limit of usability, or only work between certain times.
    Last edited by toscal; 26th August 2007 at 09:07 AM.

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    Smile re

    G'day,

    m1anh: wooha a lot of things were described, so I will go straight to the answers. I did eventually go back to the onwall card switches. As you say it's cheap and it assures that the light won't be switched off when someone is still in the room. Also did the auto close function on the door bolt, it simply opens up when you scan the card and closes when you close the door. Because there's a simple electromagnetic bolt in the door frame I had to add a button inside to open the door from the inside. It works exactly like the card reader, opening the door for a short amount of time or until you actually open the door and close it behind you.

    As for the database and the computer it doesn't handle any door locking. There's a separate PLC unit which takes care of that. Because I check the scanned ID numbers in the database I had to make such a configuration. It's also easier and more flexible to add and remove active keys, allows for activation of keys for chosen periods of time and allows historical logging. I know that some locks actually have the ID that opens it inside the electronic unit, but when you lose a key, you have to actually program the door lock to accept another one. And what about the situation when the stuff loses a key that can open for example 30 doors (cleaning ladies can carry those and not carry 30 separate keys)? you will need to change all the locks not to accept that key anymore, so it can take a while. In my opinion a database system is easier to use and you can track all the keys and the times when they were used.

    I will either use MODBUS with card readers or 1-wire -> rs232 adapter for iButtons. Here's a nice one that can handle up to 100 devices on the 1-wire network:

    HA7E

    I know that RFID can be cloned, but I didn't find any Mifare readers that had rs232 output or handled modbus. I found a simple solution to the cloning problem which is a small case for the card. It makes the card completely unreadable for any device, by blocking the electromagnetic field. It's cheap too, costs only around 3$ or 2$ when you buy a lot.

    I have one question concerning the 1-wire network, do you know how fast can I scan a 1-wire network? Also how long does it take to read the ID of the 1-wire device? You see RFID readers with modbus have bufors which hold the scanned data inside until you actually read it. With iButtons you need to hold the iButton in the reader until you actually read the ROM. So if the network is pretty big and there's a moment when for example 5 people use a reader in the same time there can be a delay. And I don't want people holding their iButtons for 5s in the reader before the door opens.

    Went with Watt Stopper US & PIR detector for bathroom lights and a 20min delay when no one is moving. I hope it's quite sensitive for even the slightest movement. Also installed an electromagnetic lock on the balcony door, so when you remove the card form the on wall switch the light goes out and the balcony door locks itself, so it's hard to actually open it from outside. There's also a curtain movement sensor in front of the windows which detects any attempts of messing with the glass, like cutting or breaking it (I know there are sensors which detect glass being broken but they don't work when you cut the glass). The sensor is being activated together with the balcony door lock. Of course when you leave the balcony door open and leave those two mechanism won't start.

    toscal: yup all the things said about RFID cards are true. The real question is how often does card sniffing take place? I mean I can give those small card cases and really make them safe. Of course you can always steal a card, clone it and use it in the hotel, but considering that the guest will report a stolen card quick, I can block it in the system and give out another card. Also no card is actually used twice for the same room, as you can set which card opens which room in the database when creating a new guest in the system.

    Your statement about using plastic cards in hotels is true. So if it's so dangerous to have RFID cards because they can be sniffed, why do hotels keep using it? In my opinion the possibility is quite low and they have their advantages, for example all the things that you mentioned.

    Thanks for the answers and for the support and ideas it's cool to have someone with experience in the security area say something

    Cheers,
    dsc.

  10. #10
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    By plastic cards I meant the ones already in use, in many hotels, which have magnetic strips on them. Just wanted to clear that point up. As you seem to think I was talking about RFID cards at one point.
    Also iButtons if used to open a lock do not need to be connected to a network and can be standalone, but this has advantages and disadvantages. Standalone will have a quicker response time but need to be programmed at the door. A solution to use iButtons would be some way of networking the door lock control to a main database, but the reader is just connected to that door lock. So for example a database of keys allowed for a lock are down loaded into the lock from a main database. So when a key is read if it is allowed the door opens. If its not it sends an alarm and does not open the door.
    As a side note:
    Also did you know that its very rare for a key card to get erased when they are handed in. They normally go into a box and get erased/updated when a new person checks in.
    A friend of mine got a memo at work saying they should not be hand back hotel key cards as they can contain too much information that could result in identity theft if the cards got into the wrong hands.

    Good luck with your project.

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