A few weeks
abck I was given a rather nice 'Black Box' RS232 tester. I
don't mean a breakout box, although one of those came with it. It mean
oen of those things that grabes the data on the TxD and RxD lines, grabs
the modem control lines at the same time, and so on. I was told that
nobody uses RS232 any more. But I can certainly use it...
Well...whoever told you that is a moron, plain and simple.
He ws jsut repoprting what he was told when it was given to him. He is
most certianly not a moron, he's a darn good embedded systems programmer.
He had no use for it (which actually suprised me), but he knew I'd use it...
FWIW. Black Box still sell the thing (DT200A) at a very high prise...
Things I didn't mention about it. It's got a Dallas RTC chip in it. When
I got it. There are 2 RS232 connectors, male and female, wired pin-pin
(alas it can't intercept and modify the data). Pins 2 and 3 are monitored
by tehe 2 channels of the Z8530, there's a relay [1] that conencts a
driver to pin 2, so the thing can run as a terminal. There's another DB25
socket on the other side of hte case. It's wired -- mostly -- as a PC
parallel port, you can sue thing unti to test parallel printers or use
such a printer to log the incoming data. Note I said 'mostly'. One pin is
an RS3-level output from one of th Z180's serial ports, another pin is
used as a serial input. This lets you control the thing remotley. There
was supposed to be an adapter included with it for this (it's not just
wires, there's a resistor -- I guess 4k7 -- in series with the incloming
data line). I didn't get it, but I soon figured it out.
[1] There are 4 relays on the PCB. They are bistable latching relays
controleld by a '374 chip, each relay coil is tied between 2 of the Q
pins of said chip, so you can energise it either way round to flip the
relay one way or the other. The 4 rleays control ; Main power on/off ;
TxD output to Rs232 pin ; TxClock output to RS232 pin (used in
syncrhonous modes) ; RTS on.
There is one bit of poor design IMHO. The firmware allows you to select a
lot of bauyd rates, includign some obscure ones that I would never need,
but it on;y goes down to 75 baud. And the thing can handle 5 bit Baudot
data (well, probably not true Baudot, but you know what I mean). Having
50 baud or 45.45 baud would be useful for that.
ObCC. That unit contains a Z180 CPU, a Z8530
serial chip (yes it handles
synchronous data too), 128K bytes of RAM, a 64K byte PEROM, and a bit of
TTL. SO I guess it's a classic computer.
Oh that could even be repurposed for even more fun things!
It certianly could. The only thing I don't have data on is the existing
firmware. ALl the ICs are standard, the LCD is a standard module, etc.
But it's quite useful to me in its present form.
-tony
