11 Sep
2007
11 Sep
'07
1:26 p.m.
Why can't they just open the box and look at the
circuitry?
That's what I normally do (and incidentally, it tells me how many of the
handshake pins on an RS232 conenctor are actually used), but then I'm me :-)
If it's got a UART, and maybe some 1488,1489
chips, then it is serial,
etc.
I don't know much of anything about electronics, but I can still usually
recognize what ports are for.
OK... i have a couple of devices here, both as it happens made by the
same company, although this interface is not specific to that company.
They each have a pair of DB25 plugs on them.
Pin 7 on the DB25s is connectoed to the system 0V rail, pin 1 is chassis
ground. The drivers on all the DB25s are 1488s, the reveivers are 1489s.
On each device _one_ of the connectors is a normal RS232 port. The other
isn't. What is it?
A clue: I had to wire up and adapter cable for one of the units. I used a
red hood on one of the DB25s and a blue hood on the other, and I had a
good logical reason for picking those colours.
-tony