A multitude of USB 'sins' can often be cured by a complete powering down
of the computer, including pulling the power cord (on desktops) and
removing the battery (laptops). A soft reboot doesn't always reset the
hardware but 10+ seconds of zero power to them usually does. In this
condition, the only power in the computer is the RTC battery.
All this test costs is time and most of the time, it works here.
Then make sure that the OS hasn't assigned it/them a new port value
(com2 instead of com5). You may have to use Device Manager in Windoze
to force it to accepting the value you want.
This is why when I built the shack computer, I went back to using real
serial ports, which are far more stable.
Good luck.
Rick nhc
On 7/18/2016 4:05 PM, Don Wilhelm wrote:
Jan,
The best way to test a USB to serial converter is by substitution with
a known good one, or by substitution of a known good working serial
device connected to the questionable converter cable.
Yes, a power surge or a lightning event can damage serial interfaces
as well as USB interfaces.
Since your USB ports on the computer seem to work, borrow a known good
USB to serial converter and try it out - preferably one with an FTDI
chipset.
If you have any other devices that use a serial COM port interface,
see if they work with your USB to serial adapter - if so, the adapter
is probably OK, but remember that in the event of a power surge,
multiple failures are possible even though in normal troubleshooting
we assume only a single failure.
You can test the USB to serial converter with a 'scope and an RS-232
breakout box, but you have to know the proper RS-232 levels to
understand what is happening. A null modem loopback cable can be
helpful if you have to proper driving software application for that
testing. I did that during my years of PC modem testing, but that was
more than 30 years ago and the software ran under DOS - not helpful now.
73,
Don W3FPR
On 7/18/2016 6:36 PM, Jan Ditzian wrote:
I have a K3 that lost communication with my computer. It uses an
Elecraft serial-to-USB converter and cable. This probably happened
during a known power surge. I also lost communication to my MDS
rotor, which uses a built-in USB cable, which I believe may also be a
serial-to-USB arrangement. I checked things out a bit, and I can
tell that my USB ports all seem to work. I also tried the K3 with
another computer and was unable to communicate with it. However, I
also tried a direct serial-to-serial cable from the K3 to the first
computer, which has a serial port, and was also unable to
communicate. I am now unsure of the location of the problem. I am
willing to go with whatever works.
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