Usb to serial rs232 converter for interface cable

[KILOCHARLIE]

Purchased an rs232 interface cable for my stag 300 plus system only to realise I no longer have a serial port on my laptop (doh!!!). Luckily I have a rs232 to usb converter cable. Tried it but I can't for the life of me get it to connect to my stag 300. Unsure if this is the cable or something I'm doing wrong.

I've installed the usb to rs232 drivers but each time I try to connect to the lpg ecu it says controller not found. I've tried reconfiguring the device to com1 just incase it'll only work on that but no luck. To confirm ignition is on in the car.

Also I did notice the official autogaz cable has the wrong colour wires when linking up to the com port in my engine bay. Instead of black/red/blue/white its black/white/red/blue. I don't know why this is so i (bravely or foolishly) spliced the wires and reconnected to see if that was the problem but still no luck.

Anyone know what I am doing wrong or is it just the converter cable? Anyone else use one?
I'm thinking maybe the voltages are wrong (12v vs 5v) and my cable is useless.

[Gilbertd]

If you bought the cable intended for your system it should be wired correctly although I do recall mention of having to swap the middle two connections on some systems. Assuming the colours mean something rather than just being whatever bits of wire the manufacturer had laying around at the time, the red wire will be a 12V output from the LPG ECU so you may have damaged the interface in the cable by swapping the wires. Some systems won't connect using a USB to serial adapter, some adapters don't work too well either depending on the chipset they use.

[kbs]

what OS?

[KILOCHARLIE]

Thanks for the replies. Any idea if the Stag 300 plus is one that can't be used?

Kbs, I'm running windows 7.

Thanks

[Brian_H]

When you say you have set the com port where have you set it (inside the stag software, or windows device manager or both?)

I'd start by checking the one in device manager first (set it to a low number if its picked something daft as sometimes happens when you have had certain devices plugged in previously) and then pick the same port inside the stag software if you haven't done so already.

[kbs]

Thanks for the replies. Any idea if the Stag 300 plus is one that can't be used?

Kbs, I'm running windows 7.

Thanks

Assuming the PC has detected the USB com port and installed any drivers it requires….
From “run box” type
devmgmt.msc

This starts device manager.
Open “ports”
Identify which is your USB comport convertor (pull it out and see which one disappears if you are not sure).
Right click the identified comport
Select “Properties”
Select “Port Settings” tab
Click “Advanced”
Confirm the comport number is a nice low value – if not and there are no other devices that require a low port number – try to change it to 1,2 or 3.
Unfortunately, Windows can get its head firmly up its fundamental orifice and prevent you from doing this (just be glad it’s not a Mac). If this is the case, let us know (or look up online un-hiding and deleting unused USB devices).

You may also want to prove the comport adapter is working – to do this link pins 2 and 3 then use a terminal program to send/receive data to/from yourself via the comport (ensure echo is off) then pull out the link to ensure your typed characters are no longer being displayed. Flow control should to be set to “none” for this test.