Thanks for the in-depth reply, Jonathon. You reminded me, once again, why I never should have done The Great Purge two years back. Packratitis is good! I threw away several truck loads to the recycling center. Lots of a ton of 8- and 16-bit cards (serial, parallel, etc.), as well as boxes of cables, and hardware that dated back to 80s, when I had a store front. I knew I would come to regret this.
I think I will stick to an RS-232 connection at the PC. One of my workstations is an old quad-core with an on-board serial and parallel port. I still have several Intel Pentium 4 PCs that could be used if I can't get the serial throughout down on the quad. It doesn't matter to me if the PC is a single-core. It only has to be a server to the M100 and accessible from the network. I will keep in mind your experience and advice. Thanks again! ~Paul. -----Original Message----- From: Jonathan Yuen <[email protected]> To: Model 100 Discussion <[email protected]> Sent: Thu, Apr 27, 2017 2:07 pm Subject: Re: [M100] Questions regarding Full Null Modem Cables, specif Serial to USB Hello, Sorry, I thought you were using a real UART on the PC. Remember the 8250? I use USB to RS-232 adapters, and haven't connected to a real RS232 port on the PC side for maybe 10 years. One which I've used is just a USB to serial adapter that I generally use to connect to a Raspberry Pi. It does 0-5 volts (not real RS-232) and I have to connect it via a level-shifter to connect to the m100. When I plug it in to my computer, lsusb reports a ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port. I can connect it directly to the Pi, and there is even a 5v line so I can power the older Pis directly off the adapter. The level shifter I've used when connecting to an M100 is a MAX232N chip with 5 capacitors to boost the 0-5 to enough to drive the M100 (I've never actually measured the voltage). I wouldn't recommend this setup since there are so many pieces but I had a lot of the bits sitting around. The PL2303 adaptor has NO handshaking so I have to jumper things on the M100 side (CTS to RTS etc). But since it was originally for a pi, there was no handhaking there, either. It did work OK with dlink if you hold the speed down. The other one I use I bought off of ebay (in China). I think it has a FTDI chip in it. lsusb reports 0403:6015 Future Technology Devices International, Ltd Bridge (I2C/SPI/UART/FIFO). This one can drive the M100 with just a null modem (which I made) that is a DB9 to DB25. I think I made the adapter with the 'normal' handshaking but I'd have to pull out an ohmmeter to check the connections since the DB25 end was sealed and I don't know where my notes are. I just checked ebay but it was so long ago it has fallen off the list of puchases.... My recollection is that you probably want the FTDI chip. A lot of places talk about USB-Serial but the serial out of these is not enough to drive the M100. I think I looked specifically for FTDI when I bought the second adapter. I seem to remember that the FTDI chip adapters cost a little more than the PL2303 ones. Jonathan [email protected] ________________________________________ Från: M100 [[email protected]] för Paul Bucalo [[email protected]] Skickat: den 27 april 2017 19:10 Till: [email protected] Ämne: Re: [M100] Questions regarding Full Null Modem Cables, specif Serial to USB I was hoping for a rationale based on experience, i.e., USB works well or not at all. Doesn't really matter much. Most likely I will make up a new cable using DB25-to-DB9. While I haven't try minicom or gtkterm, I like that the latter allows me to set my preferences through a settings file. Saves me from having to use key commands. And the DE environment on the desktops is GTK+. I will try both and see where my preference lies. Thanks, Jonathon. -----Original Message----- From: Jonathan Yuen <[email protected]> To: Model 100 Discussion <[email protected]> Sent: Thu, Apr 27, 2017 12:55 pm Subject: Re: [M100] Questions regarding Full Null Modem Cables, specif Serial to USB Hello DB25 and DB9.....Real serial ports!!! I tend to use minicom for emulating a serial terminal though I did play with screen for a while. Minicom sets the baud rate etc. [email protected]<mailto:[email protected]> ________________________________________ Från: M100 [[email protected]<mailto:[email protected]>] för Paul Bucalo [[email protected]<mailto:[email protected]>] Skickat: den 27 april 2017 15:17 Till: [email protected]<mailto:[email protected]> Ämne: [M100] Questions regarding Full Null Modem Cables, specif Serial to USB I would like to use a spare PC workstation as a repository for files and programs, to be accessed by a Model 100. I used to have a null modem cable I made up years ago. (Alas, that got thrown out in the last Great Hardware Purge.) I've read about the use of a null modem cable with a USB connector at the PC end. The workstations I could choose from all have either DB25 or DB9 serial ports, so this is a matter of what works best/easier in syncing. All my computers run under flavors of Ubuntu Linux. I do run Windows in a VM on a couple of PCs, but really have no interest in connecting via a VM and to Windows. (I understand gtkterm is a good terminal choice for the Linux side.) And lastly, in regard to buying a pre-made cable: would I be correct in assuming any product labeled "Full Null Modem", "...with Full Handshake", would be adequate for the task? TIA! ~ Paul
