View Full Version : RFID - RFID Reader Module (#28140)

01-17-2006, 05:58 AM
First of all, excuses for my awful english, right now i'm working on a RFID Project, I tried the·parallax's algorithm and they're excellent, everything on the Reader Module (#28140), but now i have a small doubt, i'm kind of newbie on this area. When i use this algorithm (RFID_basic.BS2) the one that only reads the tag (i'm using the 54 mm x 85 mm Rectangle Tag (#28141)) i obtain this tag value = 48 70 48 50 55 68 55 49 49 53, then when i use this algorithm (RFID1.BS2) the one that Reads tags from a Parallax RFID reader and compares to known tags (stored·in EEPROM table). everything work allright, but when i replace the value of the tag on this·segment :

' -----[ EEPROM Data ]-----------------------------------------------------
Tag1··········· DATA··· "48 70 48 50 55 68 55 49 49 53"··········· ' valid tags
Tag2··········· DATA··· "04129C1A1C"
Tag3··········· DATA··· "041402CCD7"
Name0·········· DATA··· "Unauthorized", CR, 0
Name1·········· DATA··· "Tag 1 (White Card)", CR, 0
Name2·········· DATA··· "Tag 2 (Oval)", CR, 0
Name3·········· DATA··· "Tag 3 (Small Round)", CR, 0

(*) tag 1 it's the one of my RFID tag.

but it doesn't work.... it says "unauthorized".

Thanx. From Chile.

Jon Williams
01-17-2006, 06:29 AM
You need to convert your string to single bytes; what you've got in your string is the ASCII codes instead of the actual characters.

"48 70 48 50 55 68 55 49 49 53"

should be:


Please double-check my coversion... I did it on-the-fly and in the middle of two other projects.

Jon Williams
Applications Engineer, Parallax

01-18-2006, 01:02 AM
U're completely right with your conversion. http://forums.parallax.com/images/smilies/turn.gif Thank You.

i found a website with all the conversion for those that doesn't know too much about it.·· <<- (doesn't or don't wich word?.)

the website it's in spanish, muaa ja jaja

Last few Questions,

1.- ·where can i find information about link this algorithm with an Access Data Base or MySQL.

2.- It's posible to obtain the exact hour in which one opens or closes the door?
Where I can look for information·about it?


Best Regards
Guillermo Díaz
From Chile

Jon Williams
01-18-2006, 01:05 AM
If you look in the RFID docs you'll see how to connect to a PC serial port. You would simply read the port and then compare that string against elements in your database. The trick, I think, is adding serial input to Access and that's not something I know about, but I know it can be done because I saw a web site just yesterday talking about it. You might give Google a try for that.

And when you've found a valid tag, it should be a simple matter of grabbing the system time -- these are now PC programming questions and perhaps beyond the scope of this forum. There's lots of good VB and VBA sites, you'll just have to do a search for the right information.

Jon Williams
Applications Engineer, Parallax

01-24-2006, 03:37 AM
"There's lots of good VB and VBA sites"

Visual Basic = PBasic?


Bruce Bates
01-24-2006, 03:50 AM
Goten -

There is absolutely no relationship between Parallax PBASIC and Microsoft's Visual Basic, and we can all thank our lucky stars for that!


Bruce Bates

Jon Williams
01-24-2006, 04:32 AM
As Bruce points out, PBASIC is dramatically different from VB.· In fact, when I do the occasional VB project I'm irritated that I can't do bit variables and easy bit-manipulation in VB!

For my March column in Nuts & Volts I did a VB project that captures and parses the Debug output from a BS1 controller.· You can find my VB files here -- they will show you how to open and get info from a serial port in VB6 (Pro):


What works nicely in VB is that anything coming in gets treated like a string.· With the RFID, you get a $0A (LF) character before the string, then you get a $0D (CR) -- so, you have nice framing characters to look for in your serial buffer.··

Jon Williams
Applications Engineer, Parallax