very nice work Take a look at this ic called the max232 it will handle the signal conversion for you
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<
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.
Last edited by Stot; 29-06-2009 at 08:45 PM. Reason: Additional Info
That is probably what this board uses. I wanted to avoid soldering as much as possible.
That other bay part number i put up is ideal. You can just crimp or connector block some cables together and get it working.
On another note, i bought a remote shutter cable for my camera, but unfortunately it doesnt work on its onw, let alone taking it apart to interface it with the chrony....
Also if you do get it working don't forget to install a timer circuit between the chrony and camera to give you some fine control. Typical timing resolution needs to be less than a millisecond I use a digital system that is accurate to a microsecond, roughly 1 millisecond = 1 foot of pellet travel (1000 fps, high but it makes it easy to remember lol).
Excellent work! Can you do one for USB?
You can do a USB one but i havent tried, I might tho. Cost is more like £15 and you may need drivers depending on what interface is used.
Nice one stot.
I've built the circuit I sent you as well and it does work but the board solution is much neater (and easier) so I've ordered one
Nice work and great post.
I got an interface cable with my Combro so have never needed to build one myself.
When I had space to tune airguns in my shed (and the time to do it), a laptop wired to a chrono was an excellent tool.
I plink, therefore I am.
if one of you gentlemen would like to make a usb fitting interface which just plugs in and doesnt need bauds and blip blaps, i for one would buy the lead.
theres a market for such a set up.
Chronys is hard coded to com 1 or 2 but you can change it to whatever you want in the chronys.dat file. i dont know if it will work but i would have thought so.
If people really want something knocked up I'll put together a parts list but I would have thought its going to come out ~£17-20 posted for a USB version.
How about one of these with a very long lead and one for a combro both connected to a PC at the same time ?
Would be good to get muzzle energy and down range energy at the same time.
Snooper601 Suspect a simple fault, or a simple engineer He who dies with the most toys wins!
QHAC Official lubricant development engineer.
Workable with the board I originally got as it has 2 seperate channels, but you would need 2 free serial ports and be running 2 seperate instances of the software.
Probably be easier to make 2 cables and use 2 computers.
I've just had a quick play with serial to usb converters, they happily remap to whatever free com port you want so as soon as the level shifter comes through I'll marry them up and see if it works. (Chronys.exe detects it ok so fingers crossed)
(I have literally dozens of the serial-to-usb interface cables, so if this works I'll happily post them out to anyone who wants one for P&P charges)