Timing Problem - Lesson Learned

General timing system discussions.
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gpraceman
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Timing Problem - Lesson Learned

Post by gpraceman » Wed Jan 11, 2006 11:20 am

One of our GrandPrix Race Manager customers had the following problem with race timing and I thought it would be a good lesson learned to pass on. While this issue was with The Judge, it could just as easliy happen with any unshielded cabling used for any other timing system or from the PC to the timer.
I appreciate all your help in trying to track down the issues we were having with the GrandPrix/Judge race setup. After much trial and error, head scratching, and general puzzlement, we found the root cause. We had an extension cord to provide power to the Judge running on top of and coiled on, the unshielded twisted pair phone cable connecting the Judge timing unit at the bottom of the track to the start switch and controller chip unit at the top. That caused delays and or drops in the signal reaching the controller unit that manifested in two major issues

1) that race data did not always make it into GrandPrix, and
2) that data that did reach the GrandPrix software had wildly variable race times for the same car, same lane (actual 4 second elapsed race time would report anywhere from 3 seconds to 9 seconds!), etc..

Once we removed the extension cord, everything worked perfectly. The data both made it to GrandPrix and the race times were consistent and accurate. To make sure this was just not pure luck and masking another problem, we put the extension cord back on/near the data cable and instantly the system went haywire again. And as expected, removing the extension cord returned functionality to normal.

So, should any other customer ever present these symptoms, they might be idiots like us and you may want to have them check this!! I appreciate both of your efforts to help educate us on the inner-workings of your gear so we had enough knowledge to troubleshoot this. Thank you both again!!
So, if you run an extension cord next to your track, run it on the opposite side as is the cable from your start switch to your timer and/or from your timer to your computer. A high voltage cable can induce currents into lower voltage systems and thus cause electronic interference (EMI).


Randy Lisano
Romans 5:8

Awana Grand Prix and Pinewood Derby racing - Where a child, an adult and a small block of wood combine for a lot of fun and memories.

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michael4262
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Re: Timing Problem - Lesson Learned

Post by michael4262 » Wed Jan 11, 2006 2:37 pm

Thanks Randy! Good advice.

A "Lesson's Learned" category could be a good idea as a Main Forum Threads topic.


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Re: Timing Problem - Lesson Learned

Post by Drag'ngoat » Wed Jan 11, 2006 2:38 pm

I have a question pertaining to the length of the cable between the Fastrack finish line and my PC. We have about a 9 foot 2-conductor cable that I believe came with the finish line but I want to have about a 30 foot cable instead so we can place the PC up near the starting line. What kind of trouble am I asking for?

Thanks



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gpraceman
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Re: Timing Problem - Lesson Learned

Post by gpraceman » Wed Jan 11, 2006 2:42 pm

Drag'ngoat wrote:I have a question pertaining to the length of the cable between the Fastrack finish line and my PC. We have about a 9 foot 2-conductor cable that I believe came with the finish line but I want to have about a 30 foot cable instead so we can place the PC up near the starting line. What kind of trouble am I asking for?

Thanks
There is no real problem doing that. You can get a longer cable from Micro Wizard.

The caution of this thread was to make sure that you put any extension cords (or any other high voltage wiring like for a solenoid) on the other side of the track than your timer and computer cables.


Randy Lisano
Romans 5:8

Awana Grand Prix and Pinewood Derby racing - Where a child, an adult and a small block of wood combine for a lot of fun and memories.

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mrvoltz
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Re: Timing Problem - Lesson Learned

Post by mrvoltz » Sun Jan 22, 2006 4:02 pm

I am happy to say the redesign of the parrellel interface timer similar to Pack 471's that I made uses a different method of comunication and is not bothered by that kind of interferance. Also I have the control circuit up by the start line and run a Cat 5 (standard computer network cable) to the finish that is only a sensor unit. Therefore the power is up at the start with the laptop and the circuit box. No other cables run near the track at all.
If interested the plans and some pictures are available on my website.
http://www.wrightzoo.com/gptimer.htm



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