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How to communicate between an unknown hardware and labview using RS232


I am a student, I have a finger print time attendance device with me. I want to develop an application in labview using tat device as only an attendance log.

all the other control is done from LabVIEW . It has an RS232 port a USB port and an ethernet port. which is the best to use for communication between device and LabVIEW ? I dont know the make of the device so how do i establish communication ?


Thank you 

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Message 1 of 8
Well, you're going to have to find out who makes it in order to get the manual. The device is essentially worthless unless you know how to connect it and what the communication protocol is.
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Message 2 of 8

Is there no other way to find out what protocol it uses ? because i dont think i can access any info abt the manufacturer

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Message 3 of 8
You don't even have any software that comes with it? If you did, you might be able to monitor communication and reverse engineer it. Since you don't even know how to plug it in, this doesn't seem likely. Is there a part number that you can Google? What happens if you plug in the USB? If it enumerates as a HID device, you might have a chance (though difficult one).
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Message 4 of 8

itried googling the part number. tried using a barcode scanner to figure out what it is, but failed to gat any info. it was a dump in college given to me by my prof to make something out of it. i guess it remains a dump since i cant access any info about it

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Do you have the rest of the school year just to figure out how to communicate with the device?


Consider the number of possibilities with the RS-232 port: Standard communications rates include 300, 600, 1200, 2400, 4800, 9600, 19200, 38400 baud, and others. You can have 1 or 2 stop bits, 7 or 8 data bits, four options for parity, several options for hardware or software handshaking, and then you get into the communications protocol, which has never been standardized. If you do not have the correct baud rate and frame size, you cannot even begin to communicate with the device.


If you can force the device to transmit (without knowing any of the above) and you are very patient and persistent, you might be able to get a good start on baud and framing by observing what the device sends with an oscilloscope. Think hours to get baud, stop bits, data bits, and a guess as to parity. If you have to send it a command to get it to reply, it will be almost impossible to guess the right combinations.


If you want to try the Ethernet port, you will need the device's address. Any of the possbile addresses used on the internet could be in there.



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Message 6 of 8

Post some pictures Smiley Happy

(and be kind, jpg with ~200k  should be fine for the start)


Next: If you connect the USB port you can read the USB ID and search the web for that. Smiley Happy


If you open the device and read the chip IDs and look for the application notes of the vendors you get more information. Re engineering is hacking fun Smiley Very Happy (If you have the time for it Smiley Wink )


Greetings from Germany

LV since v3.1

“ground” is a convenient fantasy

'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ'

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Message 7 of 8

As Henirk said:

Re engineering is hacking fun :smileyvery-happy: 



That alone might be an interesting student project.



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Message 8 of 8