On 4/9/19 8:21 PM, Thomas Morehouse wrote:
OK - looks like I wasn't clear. In Kurt's post, he writes:
"Take one probe of the meter and put it on pin 4 of the DB9 and the
other on pin 6 of the DB25. It should beep or light up (however you
meter functions to indicate a connection). Then do the same for the
DSR line on pin 6 to pin 20. And finally the RTS and CTS pins 7->5 and
8-> 4. If they are crossed in some manner, then you will not get a
beep or a light."
If the usb/serial cable is a single unit (usb at one end, DB9 at the
other),
how do I put one probe of the meter on the DB9 and the other probe of
the meter on the DB25? There's no DB25 on the cable, unless I plug
the 9-25 adapter into the DB9 - but then I can't put a probe on the
DB9. Jeez I feel dense.
I'm really sorry I can't follow this, but maybe I'm just overlooking
something really simple?
The simple thing you are overlooking is you didn't do what I said, which
is, I repeat, "ignore the fact that the usb-serial adapter looks like a
wire. pretend it's a regular serial port right on the back of an old
desktop"
Anything I say now would just be repeating myself because I already
tried to be as explicit and through as possible. Just read my last mail
again slower.
Your serial, or rs232, cable ends at the usb-serial adapter, it does not
include it. The wire on the usb-serial adapter is a usb cable between
the usb-serial adapter and the computer, not another 2 feet of rs232
connection. The usb-serial adapter is really a tiny black box that has
two entirely different connections on each side of it. Your computer
talks usb to the adapter, and the adapter talks rs232 to the M100. When
you look at diagrams for serial cable wiring, or Kurt's table of pin
numbers and connections, or read directions, from anywhere not just
here, that say to test from this pin to that pin, or to connect this pin
to that pin, those are only talking about the rs232 connection. That
DOES include any adapters like gender changers, 9-to-25 adapters,
null-modem adapters, and the serial cable itself. Those things are all
simple wire connections. They just connect some pin to some other pin.
The usb-serial adapter is entirely different. That isn't just a wire,
it's a peripheral in it's own right, like a modem. It just *looks* like
a wire because the actual device happens to be so small that it fits
entirely inside one of the plugs, and it's usb cable is built-in instead
of having a usb port. The wire is a usb connection from the pc to the
device. You don't need to check any continuity or anything for the usb
connection. In fact, you can't. There is no simple direct connection
from the pc's usb pins to the M100. The usb connection from the pc only
goes to the usb-serial adapter and ends there in the chip inside the
adapter.
--
bkw
Thanks.
Tom M.
On Tue, Apr 9, 2019 at 7:56 PM Brian K. White <[email protected]
<mailto:[email protected]>> wrote:
You don't check continuity on the usb-serial adapter. That isn't
just a
cable, it's really a peripheral like a disk drive or a printer, it
just
happens to be a peripheral that all fits entirely inside the plug
housing on one end of it. There is no simple direct wire mapping
between
the usb pins and the serial pins. Between the usb pins and the
serial
pins, there is circuit board with a chip and a few other components
which is converting and translatine between two entirely different
kinds
of signals and protocols.
You treat the usb-serial adapter as just a serial *port*, and ignore
that it looks like a wire. Just pretend it's like a serial port
built in
to the back of an old desktop.
You check the continuity of the serial cable, which IS "just a
cable".
Or, really, you check the continuity of the combined serial cable
with
any null-modem and gender-changer adapters, and treat that all
together
as one "cable".
--
bkw
On 4/9/19 6:56 PM, Thomas Morehouse wrote:
> Thanks Kurt. I'm even denser than usual tonight I guess.
>
> From earlier posts, seems the problem (102 screen dimming) is
likely
> caused by the usb/serial cable. One end of the cable is a usb
plug;
> other end is the DB9.
>
> So I'm afraid I don't know how to test continuity on the cable.
I can
> find pin 4 of the DB9 - but where does the DB25 fit in the picture?
>
> Or, are you saying to test the cable with the DB9/DB25 adapter
plugged
> into the cable?
>
> Sorry to be the dolt again.
> Tom M.
>
>
> On Tue, Apr 9, 2019 at 10:57 AM Kurt McCullum
<[email protected] <mailto:[email protected]>
> <mailto:[email protected] <mailto:[email protected]>>> wrote:
>
> There are store bought cables that work well. Brian has done a
> great job putting together a list of those cables. For my
machines
> I have a mixture of custom made cables or slim adapters. Both
> methods work and give me the pinout below. When you get the
cable
> right, your M102 will be happy.
>
> But to the question at hand, don't tear apart your cable. Check
> it. Right now you know that pins 2,3 and 5 are all going to the
> right locations. You will need to check pins 4,6,7 and 8. Since
> those are paired lines (4/6, 7/8) one or both pairs will be
flipped.
>
> If you have a multi-meter which has a continuity check on it
then
> you test both ends of the wire.
>
> Here is what I have found to work on all my machines and I
include
> this in the mComm manual.
>
> 7 Wire Cable
> PC
>
> Model-T
> DCD
> 1
> NC
>
>
> RX
> 2
> →
> 2
> TX
> TX
> 3
> ←
> 3
> RX
> DTR
> 4
> ←
> 6
> DSR
> GND
> 5
> ↔
> 7
> GND
> DSR
> 6
> ←
> 20
> DTR
> RTS
> 7
> →
> 5
> CTS
> CTS
> 8
> ←
> 4
> RTS
> RI
> 9
> NC
>
>
>
>
> Take one probe of the meter and put it on pin 4 of the DB9
and the
> other on pin 6 of the DB25. It should beep or light up (however
> you meter functions to indicate a connection). Then do the same
> for the DSR line on pin 6 to pin 20. And finally the RTS and CTS
> pins 7->5 and 8-> 4. If they are crossed in some manner,
then you
> will not get a beep or a light.
>
> Hope that makes sense.
>
> Kurt
>
>
> On Tue, Apr 9, 2019, at 7:38 AM, Thomas Morehouse wrote:
>> Thanks for the comments gents. Learn something every day.
>>
>> Kurt, on the "crossed wires" issue, what is the procedure for
>> fixing the problem? I sure don't want to pull something apart,
>> or buy even *more* adapters!
>>
>> Thanks.
>> Tom M.
>>
>>
>> On Tue, Apr 9, 2019 at 10:03 AM Kurt McCullum
<[email protected] <mailto:[email protected]>
>> <mailto:[email protected] <mailto:[email protected]>>> wrote:
>>
>>
>> What you are describing happens to me when the either the
>> CTS/RTS or DTR/DSR wires in your cable are crossed.
>>
>> Example. The CTS pin listens (checks for voltage) to
the RTS
>> pin on the other end. If you have a cable where RTS goes
>> straight to RTS and CTS going straight to CTS, then you
have
>> two ends of the cable both feeding voltage to the same
wire.
>> This causes the screen to go dim. the DTR/DSR pins can
>> produce the same issue.
>>
>> Kurt
>>
>> On Tue, Apr 9, 2019, at 5:33 AM, Thomas Morehouse wrote:
>>> Now that I've got my usb/serial link working (M102 to Dell
>>> laptop), I notice the 102's screen get quite dim when the
>>> cable is in the 102's 25 pin serial port.
>>>
>>> Doesn't need to be connected to the Dell. Just when
you plug
>>> the usb/serial cable into the 102. Unplug the cable, 102
>>> screen returns to normal visibility.
>>>
>>> Something to worry about? or just live with it? I
wouldn't
>>> have thought the usb/serial cable chip would put such a
>>> drain on the system. Happens with battery power, or even
>>> with external 6 volt poweer.
>>>
>>> Thanks.
>>> Tom M.
>>>
>>
>
