PDA

View Full Version : Should I buy this?



ScanDisk
August 21st, 2017, 07:57 PM
I need to attach a serial null-modem cable to my modern machine, but of course, it has no serial port.

I am in need of an adaptor, and an adaptor which will handle a null-modem cable fine, because the one I ordered a month ago, doesn't as I keep getting timeout errors.

I found this one.

Would it work?

http://www.ebay.ca/itm/USB-2-0-to-Serial-RS-232-DB9-9Pin-Adapter-Converter-Cable-FTDI-Chipset-1M-LED-/401384966960?hash=item5d74688b30:g:tr4AAOSwWmhZkzp w

Caluser2000
August 21st, 2017, 08:06 PM
Yes it should. What speed are you running your current on at?

ScanDisk
August 22nd, 2017, 04:59 AM
Yes it should. What speed are you running your current on at?

11152 or whatever it is.

Druid6900
August 22nd, 2017, 06:14 AM
Funny that this should come up.

I have a client that I sold a TRS-80 Model IV to and he was asking me if there was any way to connect it to a modern printer.

With the addition of an appropriate 25 to 9 pin down-size adapter, would this work?

Of course, he'd have to route the LPT output to the serial output, but, with LSDOS, that's pretty simple.

ScanDisk
August 22nd, 2017, 10:28 AM
Funny that this should come up.

I have a client that I sold a TRS-80 Model IV to and he was asking me if there was any way to connect it to a modern printer.

With the addition of an appropriate 25 to 9 pin down-size adapter, would this work?

Of course, he'd have to route the LPT output to the serial output, but, with LSDOS, that's pretty simple.

I would assume it would, my question is whether it'd work properly for thing like file transfers, or SLIP, stuff which requires a null-modem cable.

For other things, I don't see what the problem would be.

krebizfan
August 22nd, 2017, 10:42 AM
I would assume it would, my question is whether it'd work properly for thing like file transfers, or SLIP, stuff which requires a null-modem cable.

For other things, I don't see what the problem would be.

Don't know about that specific adapter but http://www.jamesfmackenzie.com/2016/02/13/use-rs232-serial-cable-and-zmodem-to-transfer-files-from-pc-to-st/ is an example of how file transfers can work over a USB to serial connection. The Atari ST isn't that different from a typical PC in regards the serial port. The tricky thing is that there are so many serial port transfer programs that setting the best options of both computers can take awhile.

I believe one can't go the other way and use a serial port to connect with a USB printer. The printer lacks the drivers necessary to handle serial port protocols.

Xacalite
August 22nd, 2017, 02:15 PM
"Support Bits per second Data transfer rates from 300 baud to 921600baud (RS232 ) at TTL levels"

This probably means that adapter's transmitter outputs 0/+5V, instead of RS232's standard -12/+12V.
Not good. Some receivers tolerate that, some don't.

Xacalite
August 22nd, 2017, 02:24 PM
http://www.ftdichip.com/Products/Cables/USBRS232.htm
These explicitly mention "RS232 level converter" or "RS232 level shifter".

Caluser2000
August 22nd, 2017, 02:48 PM
11152 or whatever it is.That'll be your problem then. You need to set it up much slower to match the old system.

SpidersWeb
August 22nd, 2017, 03:16 PM
Also USB doesn't exactly have hardware interrupts, so it's not great in situations where flow control is required (e.g. file transfers to old PCs).

From memory, FastLynx 3 managed to work around this, but most older programs would just bail out on a regular basis - even at low baud rates like 9600. I really just put USB<->Serial in my "waste of time" basket for anything other than monitoring an Arduino and stick to using a low cost Win98 era machine for computer serial stuff.

Just my two cents.

MikeS
August 22nd, 2017, 05:20 PM
Funny that this should come up.

I have a client that I sold a TRS-80 Model IV to and he was asking me if there was any way to connect it to a modern printer.

With the addition of an appropriate 25 to 9 pin down-size adapter, would this work?

Of course, he'd have to route the LPT output to the serial output, but, with LSDOS, that's pretty simple.
I doubt that it would work.

As Krebizfan points out you're going the wrong way. The 'master' driving the transfer has to be at the USB end, assumed to be a computer; the printer would not know how to set up the communication.

The USB connector on the printer is also different, and finally most if not all modern printers are dumb and rely on the computer to assemble the necessary pixel patterns to print characters etc.

You'd need something like a Pi or even an old DOS box in between.

Druid6900
August 23rd, 2017, 08:15 AM
I doubt that it would work.

As Krebizfan points out you're going the wrong way. The 'master' driving the transfer has to be at the USB end, assumed to be a computer; the printer would not know how to set up the communication.

The USB connector on the printer is also different, and finally most if not all modern printers are dumb and rely on the computer to assemble the necessary pixel patterns to print characters etc.

You'd need something like a Pi or even an old DOS box in between.

Yes, you're right, Mike, I looked at the USB printers I have and they all use the (sorta) D shaped input to the printer as opposed to the flat one.

I figured the Tandy to PC to printer route when he first asked but thought this looked easier.

Back to the drawing board.....

GottaLottaStuff
August 25th, 2017, 09:18 PM
Is the newer PC a laptop? If it's a desktop with PCI slots, why not use a PCI serial port card?

ScanDisk
August 26th, 2017, 10:24 AM
Is the newer PC a laptop? If it's a desktop with PCI slots, why not use a PCI serial port card?

Not a laptop, but a Mac Mini so essentially treated the same as a laptop.