[GreenKeys] A reliable current-loop-to-RS232 converter

[simon]

On 16-08-15 02:21, Bob Camp wrote:
> Hi
>
> The fine people “across the sea” will gladly sell you a RS232 <-> TTL converter mounted on a board with connectors.
> Depending on how picky you are it may or may not cost you as much as lunch at MacDonalds (including shipping over
> the ocean). If time is critical, the usual suspects here in the US will sell you a slightly fancier version (still fully assembled)
> for a bit more.
>
> Bob
>
>
>> On Aug 15, 2015, at 7:02 PM, drlegendre . <drlegendre at gmail.com> wrote:
>>
>> To convert the TTL level RS-232 signals to a proper bi-polar signal, you only need a MAX232 chip (or clone) and 4x 1uF @ 16V capacitors. The MAX232 directly converts back and forth between 5V TTL and the more correct +/-12V  signaling.
>>
>> Easy as pie, and the chips are like a buck or something. Let me know if you need one, I have a couple spares.
>>
>> On Sat, Aug 15, 2015 at 3:24 PM, <teletypeparts at comcast.net> wrote:
>> Justin,
>>
>> Thanks for your input.  Gabriel's 33  is  configured for full duplex, 20MA, 4 wire connection.  That's the way I sent it to him unless I made a mistake, but don't think so as the cable on the UCC-6 was already in place and likely was used on a computer before.  I just checked the connections and labeled the line cord end.  20MA is easy to check, just look at the large green resistor in the UCC-6 and the left tap should have a wire on it.  60MA, the wire goes to the inside tap.  I also tested the machine with a signal generator at 20MA, full dux.
>>
>> I don't want to confuse the issue if possible.  The 33 should work to a RS-232 adapter.  The problem is there are so darn many and they don't have a good track record.  I have seen lots of 33 owners struggle with this issue.  It almost always came down to the RW-232 adapter.
>>
>> Best regards,
>>
>> Wayne
>>
>>>
and maybe jump one conversion step with a usb to serial converter like 
the ftdi or a arduino leonardo with out of the box democode. dx.com and 
banggood.com have them in 5 and 3.3v versions
http://www.dx.com/s/serial+usb

And take a look here:

wiki.edwindertien.nl/doku.php?id=modules:telex

Simon (who implemented a version on a Raspberry Pi as the uart can talk 
any BAUD you like, for example 58baud (dont ask... long story))

-- 
Met vriendelijke Groet,

Simon Claessen
drukknop.nl