21 Nov
2014
21 Nov
'14
12:59 p.m.
So at least we're on the same page so far as
RS-232 -> 20mA converters are
concerned. I've been looking at that stuff today.. and here's something
that seems too easy.
Is there any reason that I couldn't pick up a cheap, common RS-232 to TTL
converter module (like eBay item 310624019670 - about $5) and connect the
TTL side to an opto-isolated transceiver pair like the HCPL-4100 / 4200?
The DIY schematics I've seen are essentially RS-232 to TTL converters
(using the MAX232 IC) that directly drive the 4100/4200 pair.
Like I said, seems too easy.. but why wouldn't it work?
I suspect that most, if not all, of those RS232-TTL converters are just
a MAX232 + the necessary capacitors, or something very similar.
Of course I've not tried it but I can see no reason why it wouldn't work.
On the other hand, I can see no reason not to just buy the MAX232 chip,
since you'll have to mount and solder up the optoisolators and associated
components anyway.
-tony