EMF & RFI problem on a laptop

[mracer]

I have a need for a laptop that is more resistant to EMF and RFI. I am using a Dell E1505 now but I am having a problem with it locking up. It is used on a Engine Dyno used to test Kart racing engines. The test is ran from 3500 RPM to 9000-9500 RPM. I can get to about 8000 and the program/ laptop lock up, the dyno will hold the engine at that RPM. I have tried shielding the plug wire, grounding everything several different ways, resister plug's all with no improvement. I need to be within about 20 ft of the motor to control the throttle. This is my hobby not a job, Its meant to be something fun to do but I'm about ready to throw in the towel. I have checked with others that have the same setup and it seems everyone is having the same problems. I have been told that the problem in with the mother board and that there is one out there that is much better. The problem with that is, you never know what mother board is inside. Anyone have any ideas where to start looking ? Is there a laptop that is hardened to this type of problem? Thanks Racer By the way, this is where the "racer" came from. Been in racing for the past 30 yrs.

[panic mode]

we are not involved in racing but we do a big deal of testing of ECUs and other hardware before, while and after it has been installed in cars. we had almost identical problem on some of our computers (laptops and desktops) communicating with tested devices (car ECUs). problem could not be conquered by shielding, grounding, isolation transformer or running PC on UPS powered only from it's batteries etc. it was obvious that certain computers would lock sooner that others (bunch running on one particular motherboard was quite a bit more sensitive compared to rest of the pack - older desktops ware least sensitive). surprisingly enough none of PCs would lock up even if the tested device was running and was wired to the PC - until application using that port was started. it would run no problem in our office on any PC or with any tested device - but in field, we could just count seconds until the PC would freeze. if it was just the application, one could kill it with task manager but in our case everything was dead including keyboard, mouse etc. (even mouse pointer would freeze). only way out - power down (not acceptable on assembly lines). nothing worked until we added optical isolation - and good bye problems. suddenly it didn't matter which pc was used, what or how long cable we had or who was running test. everything just worked... optoisolation is available for any port: - USB - Ethernet (ethernet switches with fiber port - or go with wireless routers). - RS232 (note, 99% of RS232 opto isolatiors only isolate Tx and RX signals but leave the control lines used for handshaking un-isolated. if those signals are used, one can route them through additional isolator).

[mracer]

PM, This is exactly what we see. I am using a USB to RS232 adapter that Land & sea recommends but still have the problem. I couldn't find any information if it is optoisolated or not. It is a Gold, model GXMU-1200. It looks to be shielded for RF and gold plated. Is there a high speed adapter that is isolated that may work? I think if it where a car engine I wouldn't have the problems I am having. It a 5 HP Briggs making 15 hp and a 6.5 HP Kohler XKE that is making close to 20 HP. Thanks for the information. racer

[TimWilborne]

I don't think we putten these in lawn mowers anymore Junior Dragster?

[Ken Moore]

Sounds like GO-Cart racing.

[panic mode]

you can either get: - USB hub that is optically isolated or - RS232/RS232 optoisolator or - new optoisolated USB/RS232 converter see www.bb-elec.com or http://www.bb-elec.com/product_family.asp?FamilyId=30 for example

[TERdON]

You could probably also use a simple wireless serial port server, like the Moxa NPort W2250 (the only one I've tried in practice). This would mean you could get rid of the usb dongle, and use the internal WiFi connection instead.

[panic mode]

sounds good to me. then you may monitor or adjust things on fly while they run laps .

[mracer]

I think I am going to try the B&B Isolated adapter. I have been tied up with more of this OEE/Plantmetrics stuff and no time to play. There is a race next weekend on the Ice at the Excel Center but I think will need to go as-is for now. There motors are on Karts most on the small dirt tracks around southern Minn. The most I have had is a Briggs Animal motor the was making 28 standard corrected horse power. They really talk to ya at 9000 RPM. Thanks everyone for the input. Racer

[mracer]

Well, I got the B&B Isolated adapter, and had a chance to try a couple test runs on the dyno tonight. It is a little better but the data isn't correct. The torque reading is low. I put the Gold brand adapter back on and the torque reads right but the Rfi is vary bad. I can do a test by hand and it works much better. But if I try and do a test in the auto mode, the computer program locks up. I really don't know where to go from here. Any Ideas? Racer

[BobLfoot]

Forgive my poor mechanics, but is the torque continuous and low or instantaneous and the B&B is delaying in reporting somehow. Possibly propagation delay or bandwidth limitations of the adapter.

[mracer]

Yes Bob, That is what I think is going on too. The dyno control is sampling at a pretty high rate. Then if you add in the PID control of the load servo the com may not have the speed needed. I am going to try and send Land & Sea a file for them to look at. May be they can see something from that. I really don't like the idea of building a room to run this in but it's looking like that is the only way to block out the RF. racer

[panic mode]

interesting... they probably use data buffering. i wasn't aware of timing issues (hard to expect high performance from RS232) but if you have adapter you know it works for you, then just add optical isolation. here is how and why http://www.robustdc.com/library/an001.pdf one common approach is to just use pair of line drivers back to back separated by optocouplers. for example following device is such circuit. there is no buffering and propagation delays are negligible. http://www.rs485.com/piso232.html http://www.rs232pro.com/rs232_iso.htm Please note that this only isolates Tx/Rx but not handshaking (are you using handshaking?) more practical approach for multiport isolation is to share power: http://www.angelfire.com/theforce/jte/opto/pt232.html