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]> 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. >>> >>
