USB Serial Adapters

JamesC · Post by **JamesC** » Mon Jul 10, 2006 7:48 am

They only come up used on my desktop - it didn't have this problem on my laptop. When I rebooted my desktop they went away and it went back to normal.

No idea where the plastic bulkhead connectors are from - my unit was from Brent - which is why I know it works. All I've done is paint it to look pretty...

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JamesC · Post by **JamesC** » Mon Jul 10, 2006 7:53 am

The way I have mine connected - I found an old power adapter - 12 volts 500mA - and cut off the plug. Used my multimeter to work out that the wire with the white line is positive. Stripped the thread off the ends and stuffed it in a Molex connector. It's nice and tight inside the terminal - the wire is held on to the connector with tape. (Didn't want to crimp it as I don't want to ruin a terminal)

I went over the board and checked voltages - they're all correct. Annoyingly I don't have an analogue meter so can't see if anything is slightly dodgy.

rmaddock · Post by **rmaddock** » Mon Jul 10, 2006 9:39 am

I'm not convinced that they are "all the same inside".

I had a cheapo cable from "the web site" and it didn't work whatever I tried to do. I could connect from an old machine with a real serial port so I knew the MjLJ was fine.

From looking at posts on this forum, I tracked down a second hand Belkin thing and that worked perfectly the first time. Nothing else changed.

bhwm · Post by **bhwm** » Mon Jul 10, 2006 10:03 pm

Obviously if Hyperterminal can't open the port, it is either in use by something else or you have a problem with the device / driver / configuration.

Assuming you can get Hyperterminal to open the port, the best way to test your serial port would be to use a serial loopback connector - to eliminate any problems with the Megajolt or wiring. This is simply a DB9 connector with pins 2 and 3 connected together (ie transmit pin connected to receive pin). You can buy them or make one easily if you have a spare DB9 female connector (the pin numbers are usually marked on the connector). You can even short pins 2 and 3 with a bent paperclip if you are very careful, have steady hands, and someone else to do the typing (though I am not recommending this).

Normally, with nothing connected to the port, when you type in Hyperterminal you see nothing on screen. With the loopback connector joining pins 2 and 3, everything you type will be looped back from the transmit pin into the receive pin and displayed on screen. If this happens then your port is definitely working properly and you know the problem is with the Megajolt or wiring. Otherwise the problem is with your serial port.

Make sure you setup Hyperterminal correctly as described elsewhere in this thread - especially make sure that you select flow control as none (ie NOT hardware or Xon/Xoff).

I have a cheap USB serial port I got off ebay, and it seems to connect to the MJLJ fine. There are probably subtle differences between different makes, but I would expect most of them to work fine in this application.

JamesC · Post by **JamesC** » Wed Jul 12, 2006 4:14 pm

Well I tried it with a proper serial cable - works a treat.

Good stuff Brent!

4600cc · Post by **4600cc** » Wed Jul 12, 2006 5:58 pm

What did you have before?

JamesC · Post by **JamesC** » Wed Jul 12, 2006 9:30 pm

USB>Serial

My proper laptop only has USB - the ancient ancient takes-20-minutes-to-load-up laptop has a serial port.

4600cc · Post by **4600cc** » Wed Jul 12, 2006 10:43 pm

So you had USB>Serial and now you got a different USB>Serial adapter. Right? The previous one should work too, only need to know how to properly install it.

JamesC · Post by **JamesC** » Thu Jul 13, 2006 7:50 pm

No - now I have a >proper< serial cable. As in a DB9 to DB9.

I don't believe that all serial cables will work - having spoken to a couple of people they don't work with everything. I am totally ok with messing about with settings and I know my stuff regards drivers etc. The cable didn't work on 4 different machines - I used every setting under the sun. Did everything by the book. I put it down to being a rubbish cable.

I have a Belkin one on order - more luck with that I hope!

MartinM · Post by **MartinM** » Thu Jul 13, 2006 9:04 pm

I guess you mean "I don't believe that all <b>USB</b> cables will work..."??

JamesC · Post by **JamesC** » Thu Jul 13, 2006 9:39 pm

Yup. typo...

4600cc · Post by **4600cc** » Thu Jul 13, 2006 10:15 pm

Nothing wrong with your previous adapter, you just don't know how to install it. But that does not mean it does not work. Sometimes things give trouble even to the best of us.

Reason?

a) You have the latest operating system.
b) You have the latest hardware.
c) You purchased a product that was made to be used on latest hardware and operating system standards.

Send it to me, I'll make it work.

JamesC · Post by **JamesC** » Thu Jul 13, 2006 10:44 pm

I have the latest operating system (XP MCE) - it was also tried on XP Home and XP Pro - both with the latest service packs - along with XP 64 bit (probably the least likely to work)

I have the latest drivers for my laptop - it's a brand new Sony Vaio. Everything is up to date.

If it's that difficult to make it work - and it only works on such a specific machine - then it's a rubbish piece of kit. End of story.

4600cc · Post by **4600cc** » Fri Jul 14, 2006 12:18 am

Send it to me I will make it work on anything that looks like a PC!!!

jimmyybob · Post by **jimmyybob** » Mon Dec 11, 2006 9:32 pm

Tell me if this is a really stupid thing to say,,,, but why not just build the magajolt with USB instead of serial.????

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