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RS232 filter. Stamp the way to go? — Parallax Forums

RS232 filter. Stamp the way to go?

SeipySeipy Posts: 6
edited 2004-10-14 17:58 in BASIC Stamp
New to the stamp community. I am not sure if I am barking up the right tree.
I have a Radio Frequency Identification System (referred to as RFID).
Currently the RFID reader is hooked to a PC. a Visual Basic program sends commands to the reader polling it.
In short terms it asks the reader do you have any RFID tag information.
The reader always responds with something.
It either sends a data string stating it has nothing or·it sends a·data string containing the Hexadecimal data from the tag it read.
The RFID reader has the ability to send data every 6 milliseconds.
I would say about 95% of the data coming back has no tag information.
Unfortunatley the PC can not process the data fast enough because it is trying to do alot of other things with the data.
So in short. I want to try and have a stamp receive the data from the reader. If the response from the reader indicates no data I do not want to send anything to the pc. If the data string includes data I want to pass it along to the PC.
All I am trying to do is pass along the information that has tag data. I do not want to pass along the responses from the reader that have no tag information.
Typlical tag information is 20 bytes long in hex format.
I hope someone can help. I have a BIG stamp programming manual in front of me. Alot to read if it won't work.
Thanks,
Dave Seip
dseip@rcn.com
·

Comments

  • Eric REric R Posts: 225
    edited 2004-10-13 01:08
    I have been looking for a cheap RFID system as i thought I would let the stamp do it all plus control any outputs as a result of a good scan. I am not saying it would work but I have wanted to try for some time now.
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2004-10-13 13:38
    Do you know what the output stream looks like? You may be able to use the SERIN's WAIT modifier to wait on a valid header, then capture the ID string. This can then be passed on to the PC.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Jon Williams
    Applications Engineer, Parallax
    Dallas Office
  • SeipySeipy Posts: 6
    edited 2004-10-13 21:40
    Hello Jon,
    Yes I know exactly what the ouput stream is. To clarify everything.
    When the RFID reader has seen no tag the reader responds with
    01 04 08 25 41 B0 00 15 B2 the response in in hex. The 00 indicates no tags.
    When the reader has tag infor it transmits the following
    01 04 15 25 41 B0 01 10 CF BE 06 00 10 00 02 A8 07 05 08 03 81 00.
    You can see that there is now a 01 after the B0 characters. This indicates it has tag information from 1 tag.
    In the event the reader has tag information for 2 tags there woudl be a 02 after the B0.
    You see the main problem I have now is that 95% of the info sent from the reader indicates no tag info. The computer chokes because it gets this string every 6 milliseconds. It would be great if I could only send the data to the PC when it contains tag information.
    I had thought the stamp was limited to 1 set of TX/RX Serial data pins. After reading today I see that any of the other pins can be used also.
    I may have the need for 2 serial ports. It would also be hard to debug if you were sending data in on the pins you woudl use to monitor.
    Does all this sound feasable?
    Thanks for your help,
    The stamp solution looks very interesting and promising.
    Dave Seip
  • K de JongK de Jong Posts: 154
    edited 2004-10-13 21:57
    Hi Seipy,

    An easy solution of your problem of "double use" of serial pins may be the USB2SER.

    This is an USB to serial adapter which uses TTL level so you can put it on any two free pins you have on your Stamp.

    I'm very happy with it, I use it in developping datalogging system where I program via the standard RS232 interface and watch and control the datalogging process via the USB link.

    I find it really nice !! (and Parallax sells them)

    Regards,

    Klaus
  • PauliePaulie Posts: 2
    edited 2004-10-14 01:05
    Seipy,
    Now would be a good time to learn Visual Basic.You could program your polling rate to the reader if desired and or filter the data in the serial port routine.
  • SeipySeipy Posts: 6
    edited 2004-10-14 08:14
    I do agree I should learn visual basic. One of the people who works for me is pretty fluent with VB. He had written the current program. Like I said the current program does alot of other things witht he data and it does not appaear to handle the data faster than 100 msec intervals.
    I figured it would not be that hard since I know the basic PC commands from back in the 80's with the Commodore 64 and Apple PC's.
    Thanks,
    Dave Seip
  • DonRDonR Posts: 6
    edited 2004-10-14 17:38
    Is your pc getting bogged down or just your VB app?
  • DonRDonR Posts: 6
    edited 2004-10-14 17:58
    Dave,
    ··· I have done very similar things in VB in the past, with almost 100 serial ports sending in data. Since this is off topic please shoot me an e-mail or give me a call and·I will be glad to discuss with you.

    Don Raczkowski·
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