Thanks Kurt. But we already know that my current usb/serial adapter (which is a single unit usb/serial cable) cause the 102 screen to dim. In other words, that's where the problem is.
So I don't see how a new null modem cable plugged into my faulty usb/serial adapter/cable will help the situation. Tom m. On Wed, Apr 10, 2019 at 12:51 PM Kurt McCullum <ku...@fastmail.com> wrote: > Tom, > > The cables that Brian is recommending will attach to your existing usb to > serial adapter. So the connection would work as follows. > > Laptop USB Port -> USB to Serial Adapter -> DB9 to Db25 Null modem Cable > -> Model T > > Kurt > > On Wed, Apr 10, 2019, at 9:46 AM, Thomas Morehouse wrote: > > Thanks Brian. Turns out your cable links weren't in my thread at all. > They were in a different thread completely which I wasn't part of, and > wasn't following. > > Here's the situation. Those two cables you recommend in that other thread > are null modem cables. Fine - but I've already learned the problem I have > is with my usb/serial cable. Soon as I plug it into the 102, the 102 > screen dims, which may be caused (I've been told) by crossed wiring in that > cable. > > So, even if I do buy another cable (one of the null modem cables), I'd > still need some kind of usb/serial "converter/adapter". There's no usb on > the recommended null modem cables, and there's no serial port on the Dell > laptop or desktop. > > Thanks. > Tom M. > > > On Wed, Apr 10, 2019 at 12:39 PM Brian White <bw.al...@gmail.com> wrote: > > In one post, I provided a link directly to two items, a specific cables2go > cable and a specific sabrent usb-serial adapter, so that you wouldn't have > to make sense of the full page where that info came from. > > And also linked that full page, which includes the startech and others. > > http://tandy.wiki/Model_100_102_200_600_Serial_Cable > > I know reading that full page might not make 100% sense, because it's a > lot of verbiage, and there are many cables listed there and they all work > for this so how do you choose, and some parts are kind of cryptic, which is > why I pulled out the two parts to get. > > For instance the shorthand I used to document each cables wiring > idiosyncracies, like "DCD<>DSR+DTR", I know that part is cryptic. When I > was testing cables and assembling the info, I just needed to get the key > details written down, and the form didn't matter. I could expand it to be > more readable later. > > What those little things are showing is how each particular cable differs > from the rs232 spec. > > For instance "DCD<>DSR+DTR" means that dsr and dtr are tied together on > one end, and connected to dcd on the other end, and that it's the same on > both ends in both directions. All other connections are according to the > rs232 spec, and you get the pin numbers and positions from the rs232 spec. > > Some time when I want to spend more time on that page, I can expand those > to a less cryptic form, (or anyone else can, it' s a wiki) but until then > at least the knowledge is documented so that later I can refer to it. It's > sort of like working notes until then. > > Mike Stein also provided a direct link to a specific monoprice cable. That > one is good too. (it's on that page too for instance) > > All other cables you randomly find from wherever, probably aren't right > without some kind of adapters, and there is no way to tell if the wiring is > right except by knowing the rs232 spec and testing the connections. > > rs232 is not a single thing, it's a spec with a bunch of options and > configurations. In order to use anything serial, you the user, actually has > to understand that spec, or, you have to take the word of someone else who > does, and says "this specific cable will work for this specific > application". Plugging in any old cable without knowing how it's wired or > what the different rs232 signals are for and how they work, will never > work. Serial is not like usb or ethernet or headphones. > > For another example of ehat I mean, even when you finally get a correct > serial cable for connecting your m100 to a pc, that cable won't be correct > for connecting to a modem, or a plotter, etc. 3 different devices, 3 > different cables, and yet all of them are valid correct serial cables even > though they are all different from each other. > > The only way to make it work is to understand that and go read about > serial cables so that you know enough that you could build your own from > scratch, or continuity test any off the shelf cable to fully understand > what it does. Or, buy one that is already known to be correct for this > particular task. > > -- > bkw > > > > On Wed, Apr 10, 2019, 7:30 AM Thomas Morehouse <nutmegfl...@gmail.com> > wrote: > > Brian - you wrote: > > " > > The Cables2Go one I linked is all the same, except it also has rts/cts, > so it works with HTERM, as well as everything else. > > And finally, the StarTech one I linked, is also all the same, but > without shorting DCD to DSR, or shorting DTR to DSR, which means that > one should cause the least possible drain on any possibly weak power > rails in the M100. > > All this mystery has already been completely figured out and nailed > down. One mouse click and $7 later and you're done." > > I've gone through all your posts in this thread, and find no links for > Cables2go or StarTech. > > I'm absolutely going nuts here, trying to figure out how to do things, and > how to follow advice. One post with advice raises a question, someone else > tries to answer the question, then someone else tries to clarify the answer > to someone else's question. Really helpful to some, but frustrating to me. > > Which post had those two links for the proper cables? I've now got two > usb/serial cables which don't seem to work, plus several male/male, > female/female, and DB9 to DB25 adapters. Total so far: $100. > > As I can't find the links Brian referred to, I don't want to guess and buy > yet another thing which might not work. > > Thanks. > Tom M. > > > > > On Tue, Apr 9, 2019 at 9:34 PM Kurt McCullum <ku...@fastmail.com> wrote: > > > Tom, > > Looks like you will need to either build or buy a cable. My two cents is > below but I'm sure others will chime in. There are several options out > there. > > Here is a description of what I do with all my Model-T units. I start with > this DB25 to DB9 adapter which is just a regular DB9 to DB25 converter. I > attach these with some 2.5mm (should be 2.6mm) screws to the Model-T so its > always attached. > https://www.sfcable.com/db9-female-to-db25-male-serial-mini-adapter.html > > Then I put one of these adapters in between the DB9 serial port and the > 9-25 adapter which creates a null modem cable. > > https://www.sfcable.com/null-modem-adapter-db9-db25/db9-male-to-female-null-modem-mini-adapter.html > > For my T200 I have remove pin 1 from the null modem adapter to make it > happy but that's a quick fix with needle nose pliers. > > Everybody has there preference on cable setup so eventually you will come > up with a solution that works for you. Sounds like what you have is working > for text transfers so that's a start. > > Kurt > > > On Tue, Apr 9, 2019, at 5:59 PM, Thomas Morehouse wrote: > > Thanks Kurt. > > Testing the DB9-DB25 adapter only - not the usb/serial cable - I have > continuity NOT from pin 4 of the DB9 to pin 6 of the DB25. I have > continuity from pin 4 of the DB9 to pin 20 of the DB25. That's using the > numbers printed at the pins themselves. > > Should I even bother testing the others you suggest? Sounds like the > adapter already fails the test. > > Tom M. > > > On Tue, Apr 9, 2019 at 8:48 PM Kurt McCullum <ku...@fastmail.com> wrote: > > > Ignore the USB to serial piece of the puzzle. As Brian said, it's just a > serial port. Test the 9 to 25 adapter. One end will be female so it's > easier to put something like the end of a paper clip into one hole at a > time then put the probe on that. > > Kurt > > On Tue, Apr 9, 2019, at 5:22 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? > > Thanks. > Tom M. > > > On Tue, Apr 9, 2019 at 7:56 PM Brian K. White <bw.al...@gmail.com> 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 <ku...@fastmail.com > > <mailto:ku...@fastmail.com>> 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 <ku...@fastmail.com > >> <mailto:ku...@fastmail.com>> 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. > >>> > >> > > > > > > >
