[ntp:questions] YEA! My Sure Electronics GPS just arrived.

Ron Frazier (NTP) timekeepingntplist at c3energy.com
Tue Mar 27 01:54:13 UTC 2012

On 3/26/2012 5:00 AM, DaveB wrote:
> In article<4F6D3E94.4080902 at c3energy.com>,
> timekeepingntplist at c3energy.com says...
>> Hi all,
>> I just discovered an interesting thing about the Sure board's serial -
>> USB converter.  I went ahead and installed the driver.  With this serial
>> - USB converter, which is a Silicon Labs CP210x chipset, no matter which
>> USB port I plug it into, it becomes COM6, which was the next one
>> available.  With the Prolific based devices, including the TU-S9 and the
>> BU-353, each subsequent USB port I plug into becomes a new com port, so
>> those devices became COM3, COM4, and COM5 respectively as I plugged them
>> into succeeding USB ports.  I can see pros and cons either way.
>> With the Prolific way, if I move the device to a different port, I have
>> to have a different setup in the ntp.conf file, although you could
>> probably have multiple setups, and if nothing is attached to a given
>> port, then it gets ignored.
>> With the Silicon Labs way, I only have to have one set of configuration
>> options in ntp.conf.  However, what happens if I plug in another device
>> with the same chipset?  I'm assuming the next one will become COM7.
>> But, now, if I unplug both and plug them back into the same ports, but
>> in the opposite sequence, I'll bet the original 1st device will now be
>> COM7 and the original 2nd device will be COM6.  I can see how this would
>> cause some problems.
>> I have not tested yet whether this board's USB port has a built in
>> driver in Linux.
>> Sincerely,
>> Ron
> Ron.  To "fix" wandering com ports in Windows, take a look at:-
> https://fedorahosted.org/fldigi/wiki/Documentation/HOWTO/Windows_USBSeri
> al
> (or:- http://preview.tinyurl.com/8592zvp  Goes to the same site above.)
> Hope that helps a bit.  Maybe there are similar tweaks in Linux?
> Dave B.

Hi Dave B,

Thanks for sharing this.  I'm not sure I'm going to tweak the ports, but 
at least I'll know how.  It actually confuses me a bit.  Here's a quote 
from the site:

quote on -->

When you later re-connect the *same* USB<>Serial adapter, to the *same* 
USB port on the PC, it will re-appear again at the Com Port you just 
assigned it to, i.e. It's a "Sticky" setting. But, if you have a 
different adapter (even the same make & model) or connect the same one 
to a different USB port, you'll have to do all this again.

<-- quote off

Here's what happened to me.  When I got my BU-353 GPS, which uses a 
Prolific chip set internally, I plugged it into each USB port in turn, 
and here is what happened:

Plugged into USB1 - was assigned to COM3
Plugged into USB2 - was assigned to COM4
Plugged into USB3 - was assigned to COM5

Then I tried my Trendnet TU-S9 serial - USB adapter, which uses the same 
chipset.  From the above verbiage, I would expect to see that assigned 
to COM6, COM7, and COM8.  But that is not what happened.  Here is what 
actually happened.

Plugged into USB1 - was assigned to COM3
Plugged into USB2 - was assigned to COM4
Plugged into USB3 - was assigned to COM5

This, in fact loaded the same driver as it did when I plugged in the 
BU-353.  So, it appears that they're not reading any sort of serial 
number, since it didn't recognize that I'd plugged in a "different" adapter.

To make matters even more confusing, if I plug the USB cord from the 
Sure board into each port in turn, I get this:

Plugged into USB1 - was assigned to COM6
Plugged into USB2 - was assigned to COM6
Plugged into USB3 - was assigned to COM6

None of this is a big deal at the moment.  However, if I did have two 
Sure boards, and I wanted to hook them up at the same time, I would 
definitely want them to appear on different COM ports; and, if I swap 
the cables, it would be preferable that each still appear on the same 
COM port it did before.




(PS - If you email me and don't get a quick response, don't be concerned.
I get about 300 emails per day from alternate energy mailing lists and
such.  I don't always see new messages very quickly.  If you need a
reply and have not heard from me in 1 - 2 weeks, send your message again.)

Ron Frazier
timekeepingdude AT c3energy.com

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