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  1. #1
    Join Date
    Nov 2008
    Location
    Stevenage
    Posts
    643

    Chrony PC Interface Cable project.

    Hi,

    Leading on from SpikeG's thread about adding a remote to your Shooting Chrony, I was already investigating making a serial cable to connect up to a PC for my own ammusement.

    The number 1 google result is the noplabs interface but unfortunately it uses not very obtainable MOSFETS to build.

    Anyway long story short I had bought a pentium laptop with a serial port on the evilbay for £9.99 + £9.50 post ready for my project and set about building the noplabs interface. It didnt work for me, probably as i couldnt get the gate protected MOSFETS then i got to thinking about the REAL problem with connecting the Chrony to a PC.

    That problem is converting TTL signals to RS232 signals. They run different voltages so you need to do something in the cable to deal with this. Then I thought, someone MUST be doing this already... Quick evilbay search and I found a board that did just that for less than £5 delivered.

    Ordered it 4 days ago and it arrived today, so I butchers an old serial cable and a headphone jack and attached them to the board.

    >INTERFACE PIC 1<
    >INTERFACE PIC 2<
    >INTERFACE PIC 3<

    Set up the PC, loaded the software i had found and.... Whoooop success!! The chrony was sending the fps info to my laptop and the software was converting it to ftlb and joules.

    If I were to do this again I would buy evilbay part 330340621351. This way you dont need to worry about wiring the 9 pin cable in, just the headphone jack, which is just 3 cables anyway. You can solder the cable from an old computer CPU fan or floppy drive power connector to the headphone jack in the right order and it will work. Could be build even with wire twisting or connector blocks for under a tenner.

    You need to connect the tip to TX the center to RX and the base to GND

    >JACK CONNECTING PIC<

    I connected it all up and ran it through a test using my HW45 and some AAF pellets. I set the weight of the pellet to 15.9 in the program and fired off 10 shots.

    >TEST RIG PIC<

    >TEST VIDEO<

    If you want to do any of this you need to set your COM port settings to 4800 baud, 8 data bits, no parity bits, 1 stop bit and no handshaking.

    You can also connect up Hyperterminal or any terminal program directly to it and it will stream the data straight to the screen also.

    Hope this helps some of you out there. Ill try and help if I can but im just an experimenter not an expert.

    Almost forgot. The software im using will save each 'session' as a new line in a text document. This is saved as a list of CSV ft/s values which can be taken into Excel or Open Office to do sums with, work out averages, print graphs and the like.

    >GRAPH EXAMPLE<

    Cheers
    Stot
    Last edited by Stot; 29-06-2009 at 08:45 PM. Reason: Additional Info
    Guns: SLR98 - Phoenix - Ultra - HW45 - P800
    Chronographing: www.chronoconnect.com

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