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- Com1 port problems
February 28, 2006, 5:16 pm
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Can anyone tell me where the COM1 port is located in a PT-5VMD
motherboard? I need to connect some hardware to the com1 port, but
though windows tells me the port is fine, the software tells me it
can't detect anything. It turns out that the com1 cable was free
hanging in the cabinet, and i need to know where to connect it
Also, is there a simple test to tell me if everything is fine with the
Re: Com1 port problems
The www.azzausa.com site is still alive, but the info there is useless
for answering your question.
Maybe there is a nine pin header socket on the motherboard ?
I cannot find a high resolution picture, and this is about the
best there is.
There are at least two different standards for adapter cables.
These devices convert from a nine pin (2x5, one pin missing)
header, to a PCI slot bracket mounted serial port connector.
Hope that points you in the right direction.
Re: Com1 port problems
Well, first of all, RS232 signals cannot be damaged by connecting
them together. If you were to accidently connect the TXD of one
port, to the TXD of the other port, no permanent damage should
result to the RS232 driver.
The test I would use, is to open a Hyperterminal window with
respect to each COM port. One Hyperterminal window for COM1
and one Hyperterminal window for COM2. Connect the TXD of one
header, to the RXD of the other connector. When the cursor is
in the Hyperterminal session of the connector you are using
the TXD pin on, type a character. The character should show
up in the other Hyperterminal window.
You can connect the two connectors bidirectionally, like this.
Then, your two Hyperterminal windows can carry on a "chat"
session. Characters typed in one window, should show up
as received in the other Hyperterminal window, and vice versa.
COM1:TXD >>>>>>>>> RXD:COM2
COM1:RXD <<<<<<<<< TXD:COM2
It is also possible to tell a bit about the wiring, by
looking at the voltage on the pins. I always have to
refresh my memory, but I believe the TX has one voltage
value, and the status signals have the opposite voltage
value, in the idle state. Also, if you connect an analog
voltmeter to the TX pin, you can sometimes see the
needle on the meter deflect, each time a character is
typed. So there are little tricks like that, for
examining an unknown header.
This guy tried to figure out the wiring on his
P4C800-E serial ports. He has a little test program.
For the two Hyperterminal windows, you would want the
two serial channels to have matching parameters. Like
9600 baud, 8-N-1 (8 data bits, no parity, 1 stop bit ?).
Its been a while since I've used RS-232.