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From: tnixon@hsfmsh.UUCP (Toby Nixon)
Newsgroups: comp.dcom.modems
Subject: Re: CTS->XON/XOFF
Message-ID: <3506@hsfmsh.UUCP>
Date: 12 Jul 90 16:06:17 GMT
Sender: daemon@hsfmsh.UUCP
Organization: Hayes Microcomputer Products, Inc.  Norcross, Georgia
Lines: 37

In article <8635@ubc-cs.UUCP>, Robert Lin writes:

- Does anyone know if there is a device that converts a hardware hand-
- shaking device into XON/XOFF protocol? 

Hmmmm.  The Hayes Transet 1000 does that just fine (including giving 
you 512K of buffers!), but we don't see it anymore.  What you need 
to get is a serial-to-serial buffer box from some place like Inmac 
or Black Box Corp.  These can usually be configured to have 
different flow control methods on the two ports.  Black Box has 
something they call a "Micro Print Spooler" for $190 in a 
serial-to-serial version.  Inmac has an interface converter that, 
with 0K buffer memory, costs only $125; it has both parallel and 
serial ports, bidirectional, with flow control conversion at up to 
38,400bps.  I think the Inmac is closer to what you need.

- On the same note, has anyone had trouble with XON/XOFF at speeds
- greater than 9600? Everything seems to work fine at 9600, but when
- I crank it up to 19200, something screws up and the buffers get
- overflowed.

It's probably dependent on the device -- the depth of the FIFOs in 
the UART, the interrupt latency in the operating system, the 
priority of comm interrupts as opposed to others, etc.  I've run 
XON/XOFF at 38,400 with no problems, but on a device that has deep 
FIFOs in the hardware.

	-- Toby

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