[Klug-general] TTL to RS-232 advice

Mon Jan 5 14:16:15 UTC 2015

Hi James,

The stuff from the UK is made in China most of the time. I've never had an
issue with these serial ports, I use them for my amateur radios and other
things.

I think I know just the beast.

http://www.ebay.co.uk/itm/New-PL2303HX-Converter-USB-To-RS232-TTL-Serial-Cable-Adapter-Modul-/131269434836?pt=UK_Computing_Other_Computing_Networking&hash=item1e90449dd4

I've used these a couple of times. Ubuntu recognises them no problem
(Windows can be an issue).

You can get them from Amazon but they will be made in China (what isn't?).

If you prefer something which will also work with Windows, look for FTDI or
CP210? (eg CP2104) chip ones. The Prolific chipset ones (PL series) can
have driver issues with Windows.

I've also used ones like this:

http://www.ebay.co.uk/itm/Convenient-Module-Serial-Converter-USB-2-0-to-TTL-UART-6PIN-CP2102-STC-PRGMR-/271424127737?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item3f322382f9

The first one has the advantage that is it all 'sealed' and has a cable.

You can't really do any damage, unless you short something to the power
supply.

They will  'connect' as serial tty devices and you can set the baud rate
etc. as normal.

I assume you are in Kent, are you close to Medway? I'm near J4 of the M2.
You can borrow one to try, if you like.

Brian

On 5 January 2015 at 13:46, jwmartnet . <jwm.art.net at gmail.com> wrote:

> On 5 January 2015 at 00:11, Brian Reay <brian.reay at gmail.com> wrote:
> > What are you trying to do?
> >
>
> View TTL serial console of QNAP device on Linux PC.
>
> > In particular, does the device you wish to connect to (not the PC, the
> other
> > 'end') have RS232 or TTL levels? If it is TTL and just Tx and Rx data (
> plus
> > ground) then a USB device like I mentioned should be fine.
>
> Yes TTL, with TX & RX, plus a green VCC cable. I found another page
> for achieving similar with freeBSD, saying to look for FT232 based
> chips for USB connectors.
>
> Some of them say 3.3v & 5v. Is the 5v the USB side, and the 3.3v the
> TTL side? Or some mention a switch - is that to switch between 3.3v or
> 5v?
>
> Are the cheap items shipped from China risky? (Hi-powered bicycle
> lights from China have a bad rep for exploding batteries,
> over-charging, etc).
> £2 from China or £10 from UK.
>
> Then am I right to guess the items listed for the Arduino might be a
> good choice? Quality, reliable UK based distributor, etc.
>
> > It will appear as
> > a serial device under Linux just like any other serial port. All the ones
> > I've used, Ubuntu has had the drivers  already installed.
>
> Thanks for your help.
> James.
>
> >
> > Brian
> >
> >
> > On Sunday, 4 January 2015, jwmartnet . <jwm.art.net at gmail.com> wrote:
> >>
> >> Thanks for your replies, but I'm clueless about electronics (and
> >> evidence seems to be stacking up against me in related areas too).
> >>
> >> The USB things look preferable, and avoid the need to get a serial
> >> cable (and enable the serial port in pc bios) ... I just don't know
> >> what the right thing to get would be. The product description in the
> >> second of those ebay listing you gave, Brian, doesn't fill me with
> >> confidence!
> >>
> >> Thanks.
> >>
> >>
> >>
> >>
> >> On 3 January 2015 at 16:53, Brian Reay <brian.reay at gmail.com> wrote:
> >> > They are bidirectional in that that the inputs RS232 "side" are
> convert
> >> > to
> >> > 3.3V TTL and the inputs on the 3.3V TTL side.
> >> >
> >> > You mentioned USB, you can buy Serial USB ports of Ebay (and Amazon)
> >> > which
> >> > have a TTL level output. They are a simple serial interface, ie little
> >> > if
> >> > any data control signals.  'Flying lead' ends.
> >> >
> >> > I've used ones like both of these:
> >> >
> >> >
> >> >
> http://www.ebay.co.uk/itm/F04879-PL2303HX-USB-Transfer-to-TTL-RS232-Serial-Port-Adapter-Cable-Module-/141130969609?pt=UK_Replacement_Parts_Tools_Repair_Kits&hash=item20dc0fb209
> >> >
> >> > OR
> >> >
> >> >
> >> >
> http://www.ebay.co.uk/itm/New-USB-2-0-to-TTL-UART-5pin-Serial-Converter-Module-5pin-cables-CP2102-STC-/400644576263?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item5d48471407
> >> >
> >> >
> >> >
> >> > Brian
> >> > www.g8osn.net
> >> >
> >> >
> >> >
> >> > On 03/01/15 16:35, jwmartnet . wrote:
> >> >
> >> > Hi,
> >> >
> >> > I want to connect a serial console to my device but need a bit of
> advice
> >> > before purchasing components.
> >> >
> >> > According to the article linked below, I need a ' 3.3V TTL to RS-232
> >> > level
> >> > shifter'
> >> >
> >> > http://www.cyrius.com/debian/kirkwood/qnap/ts-219/serial/
> >> >
> >> > Do these converters work bidirectional? Or does it specifically need
> to
> >> > be
> >> > 3.3V TTL to RS-232 and not RS232 to 3.3v TTL?
> >> >
> >> > Anything to avoid?
> >> >
> >> > Probably wishful thinking, but.. I guess TTL to USB wouldn't work
> >> > without
> >> > intervening electronics?
> >> >
> >> > Cheers
> >> > James
>
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-- 
*Brian Reay*
www.g8osn.net
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