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Troubelshooting a serial communication problem

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Newbie level 6
Aug 20, 2009
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rs232 hints

I've my own circuit whitch controlling a cash box(open and close) my problem starting when computer off and then on at startup the box open auto, I think my problem with POST which checked the hardware

rs232 problem

you have to give info about the design: hardware and software to be able to help. Remember it is not easy to troubelshoot with nothing in hand

Re: rs232 problem

By "computer" do you mean a PC running Windows? If so, it could be the common problem that Windows checks for a serial mouse during boot up. To get around this you can edit boot.ini to include something like:


This would apply to all ports. You can tell windows there is no serial mouse on just one port like this:


Or multiple ports by listing them like this:


Re: rs232 problem

Thank u everybody

when PC booting ,it check for hardware DTE DCE and other pins activated for a while and quickly .

Ok I'll send my circuit later

Added after 13 minutes:

here is the circuit which work fine .
Note that :my problem is not with xp because just turn the PC on The box open(solenoid open)

Added after 3 minutes:

Added after 57 minutes:

rs232 problem

no the problem does not seem to be from the hardware.
My question is what software are you using vb?
As mentioned the pc checks the peripherals at start up for example for the mouse the pc sends a signal and waits a signal from the mouse the mouse sends the ascii M telling that I am here so that communication starts.

check this book about serial port it is good

Re: rs232 problem

Good Morning everybody

I've used vb6 and I'm professional with controlling for a long time, I've designed and fabricated PCB boards with no problems ,I'm new with serial port and also the same thing happened when u use the parallel port ,when the system booting a random data appears this make machines on these ports to be worked like a crazy ,I can solve this problem by electronics but this need more components and I want to know if there 's a command or switch like /NoSerialMouse:COMx and this operate only when operating system control the system and not at Booting.

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