Re: Serial port

On 3 May 2005 09:43:42 -0700, frb78@xxxxxxxxx (Fred) wrote:

>After my question on the parallel port, I must ask you something about
>the serial port. Why I cannot see on my scope the data signal if I put
>my scope directly to the pins. To see it, I must connect the serial
>port on an other device and then, put the scope on the line.

---
Connect your scope ground to SIGNAL GROUND in the serial port
connector and then connect the probe input to either RX DATA or TX
DATA. Center your trace and set the vertical sensitivity to something
like 5 volts per box. Set your sweep speed for a convenient display
of the data rate you're expecting and set the sync to auto.

That should get you started, and then you can fiddle with the settings
all you want. Be aware that you'll be looking at data constantly
changing in time, so unless you're sending (or receiving) a repeating
pattern and you can get the sweep speed and sync set up just right you
won't see a stable display.

--
John Fields
Professional Circuit Designer
.

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