In article ,
 bob prohaska  writes:
> Dave Liquorice  wrote:
>> On Mon, 8 Jan 2018 20:34:17 +0000 (UTC), Kiwi User wrote:
>>
>>> A different make of USB-serial converter?
>>
>> Worth a try, I had a PL2303 based convertor connected to an APC UPS.
>> Every so often the adpater would disconnect from the USB and
>> reconnect breaking the UPS Tools monitoring...
>>
>> Got a FTDI FT232L based convertor and not had a sniff of the problem
>> since.
>>
>> Curiously I still have 3 of the same PL2303 adpaters in use with
>> other devices without a hitch. Yes, I did try some of those with the
>> UPS and they also failed in the same way.
>>
>
> It looks as if the problem is solved. The fix was to add pulldown resistors
> to ground from the PL2303's rx and tx pins. It now seems to work with the
> ttl-rs232 level shifter down to 1200 baud. At 300 baud about one character
> in ten is garbled. At 110 baud the loopback test fails completely, but that's
> ok 8-)
>
> Perhaps the same fix would help with your UPS.

There are lots of products using counterfeit PL2303 around, which
often don't work to spec.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

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