Yet another "Can't Communicate" thread.

bobclevenger · Post by **bobclevenger** » Wed May 23, 2012 10:25 pm

Hi,

My MJLJ/E installation on my 440 MoPar engine is working, but I think I may need to tweak the advance map a bit. So, I tried hooking up my laptop and usb-to-serial adapter again ... and it doesn't work now. OK, that laptop may have USB port issues, so I installed the configurator software on my newer HP Slate 500 tablet (which runs some version of Windows 7). The software installed just fine, and seems to run well. OK, now to connect the USB-to-serial adapter. First I installed the HL-340 driver with no problems and then connected the adapter to the USB port on the HP Slate 500. Oops... Windows tells me thet there is something wrong with the device. OK, It's been kicking around for a year now so it's possible it has become damaged. I'll get a new one. Hmmm... I can't seem to find those adapters for sale on your web site. No problem, I'll just get one of the ones you say will work from someone online (turned out to be Amazon.com).

So I got a new adapter with the Prolific chipset and once again installed the driver that accompanied it according to instructions (install driver before connecting adapter). All went smoothly. When I plug the adapter into the HP Slate 500 it shows up in Device Mangler as a Prolific device on COM3. So far, so cool.

Ah, but when I connect the adapter to the Megajolt, fire up the car's ignition, and open the configurator program I get the dreaded timeout message at the bottom of the window.

Yes, the MJLJ/E was powered up.
Yes, all cables are in good shape and connected properly.
Yes, I've set the port in the configurator to COM 3, same as the adapter is set.
Yes, I've tried other COM ports.
Yes, I've tried altering the baud rate, data bits, parity, and all that other RS-232 stuff.

Is there something I've forgotten in the last year?

I have finally found the URL for your page that has the USB-to-serial adapters for sale on it and I have ordered another one. Just in case.

Post by **brentp** » Thu May 24, 2012 6:15 am

Hi Bob,

Sorry you're having problems. Can you communicate with the Megajolt using a PC with a built in serial port? You may need to remove the Megajolt and power it up on the bench using a 9V battery.

bobclevenger · Post by **bobclevenger** » Thu May 24, 2012 9:00 am

Hi Brent,

I do not have any portable computers with actual serial ports. I'm not even sure that any of my non-portable computers have them.

I suppose I COULD remove the MJLJ/E from the car, but that would disable the car until it could be reinstalled. The unit runs the ignition well, so I assume that it is actually getting power from the car's 12 volt battery (which is new and fully charged, by the way).

bobclevenger · Post by **bobclevenger** » Fri May 25, 2012 3:40 am

The above doesn't mean I'm unwilling to do it --- it just means that I'd prefer to make that a last resort.

Swedge · Post by **Swedge** » Sat May 26, 2012 6:05 pm

most pc's have a serial port on them, best to test them like that first to make sure its not an ecu problem

9/10 times its the usb adaptor but it can be something else like mine

bobclevenger · Post by **bobclevenger** » Thu May 31, 2012 12:46 am

OK, I've got it working now.

I lugged a desktop computer, monitor, and 120 VAC power cord out to my car and fired things up. At first I had no communication.

Not good! Grasping at straws, I tried changing the DB-9 to RJ-11 cable. Voila! The systen now worked.

The pretty new DB-9 to USB cable clearly was somehow nonfunctional. But it turns out there were two problems, and as so often happens with more than one problem each one masked the other when troubleshooting.

1. The USB-to-serial adapter that I got from Amazon.com won't work with the MJLJ/E unit even if everything else is OK. It is a Prolific chipset, but they must have changed the chipset.

2. The DB-9 to RJ-11 adapter cable that came with the new USB-to serial adapter (see above) was wired wrong for the MJLJ/E unit. It was just about backwards.

This is a well-made cable, so I rewired it.

2a. When rewiring the above cable I had no way to conveniently connect pins 3&4 (Autosports Labs numbering) or 4&5 (everybody else's numbering) on the RJ-11 connector together as they are shown on Autosports Labs website. I tried just connecting the three wires from the DB-9 connector (pins # 2, 3, & 5) to pins # 1,2,& 3 (Autosports numbering) or 2,3, & 4 (rest of the world numbering) on the RJ-11 connector, hoping that the connection between pins # 3 & 4 (Autosports Labs numbering) or #4 & 5 (standard RJ-11 numbering) is made internally inside the MJLJ/E as well as at the cable. It worked, so that must be the case.

Yes, folks, the pin numbering on an RJ-11 connector usually counts ALL pin positions, even those that are not actually used. That means an RJ-11 connector has SIX pin positions numbered 1-6 -- even those RJ-11 connectors that only have 4 positions wired up. A 4-pin RJ-11 connector uses pins # 2, 3, 4, & 5 leaving pin 1 and pin 6 empty.
On the page that Autosport Labs shows you the wiring for the RJ-11 to DB-9 cable they only count the 4 positions on the RJ-11 connector that are actually used.
This is not a problem unless you are making up your own cable, and not even then as long as you are aware of it.

BIG thanks to Autosports Labs for helping me get this working, especially for testing out the USB-to-serial adapter that I bought before shipping it to make doubly sure that it wasn't the source of my problems.

And just to be clear, the HP Slate 500 works just fine after I got the above things fixed.

Post by **brentp** » Thu May 31, 2012 9:15 pm

Oh wow- great to hear you got it working! Didn't realize you had a different RJ11 adapter.

On a related topic, I ran in to some weird issues while working on the RaceCapture configuration app - I'm using the same serial port library I'm using with the Megajolt software, and ran into what might be some of the weird timeout issues that other people have seen with certain USB to serial adapters.

I switched it out for a different library, with some of my own custom updates, and have observing more reliable data transfers. I'm thinking of releasing an update to the Megajolt software with this new library for people to test out.

bobclevenger · Post by **bobclevenger** » Fri Jun 01, 2012 12:01 am

Well, I'm just about to start logging data on a few drives around town and over to Tahoe. There are a few fairly steep grades between here and Tahoe, so I should get pinging if I ever will (and then tweak the advance back at that point). Next step will be trying to make a map for running on regular gas if premium is unavailable (have to use that second map for something.