We've had them, and there was just some recent discussion about them a few weeks ago here, I think the main serial chip that was used was discontinued and the replacement was not 45.5 baud compatible or something.

Jeff

On Dec 10, 2021, at 7:10 PM, ad7i <[email protected]> wrote:


I'm not sure what others would be interested in the way of features, if such a device was to be created, but I was thinking about the following:

Computer to TTY: USB at standard serial speeds of 2400 to 9600 bps.   Ideally with XonXoff flow control and RTS/CTS flow control for the downstream path (however, there are windows driver issues with flow control on USB<->Serial devices).

Downstream and upstream functions are full duplex.

Downstream functions:
  • Convert ASCII to 5 unit Baudot/Murray codes: ITA#2, US MIL, others?
  • TTY output speeds of 60, 66, 75 and 100 WPM.
  • Convert ASCII LF to Baudot CR CR LF, ignore ASCII CR
  • Binary Mark/Space output that can open/close HV 60mA loop circuit, polarity independent
  • Hi Tone AFSK Mark/Space output (to drive TU in those cases where someone wants to use or demo a TU with their TTY).
Upstream Functions:
  • Binary Mark/Space current sense input of HV 60 mA loop circuit, polarity independent
  • TTY input speeds of 60, 66, 75 and 100 WPM.
  • Convert Baudot/Murray codes (ITA#2, US MIL, others?) to ASCI

Also could do a motor control.  Start motor when characters are in downstream queue (with 2 second startup char output delay for the motor to stabilize) and then motor off when no characters are in downstream queue for more than 10 seconds (or whatever time is wanted).

Assuming the printer has sensors for paper out and paper jam, it might be possible to include an AnswerBack function, if that might be useful. 

Paul, ad7i

On Fri, Dec 10, 2021 at 2:09 PM ad7i <[email protected]> wrote:
I don't have exactly what you are describing, but I've been doing a lot of PCBoard layouts for things that include USB to serial converters and microcontrollers. My most recent task is an electronic selector magnet driver (meaning it doesn't have a high voltage loop per se, but instead uses lower voltages (and small limiting resistors) to get the magnetic flux up to full value in a couple of milliseconds).

If Greenkers were willing to come up with a set of requirements (fewer is better than more) I think I should be able to come up with a simple PC Board that functions as a USB to HV Loop interface with ASCII to BAUDOT conversion included.  PC Boards fabricated in China are surprisingly inexpensive.

Paul, ad7i


On Fri, Dec 10, 2021 at 1:39 PM chris johnson <[email protected]> wrote:
Anyone making a batch of adaptors for usb to model 15 use????  Or have any already made for sale????
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