[Ham-Mac] USB Serial adapters

[Don Agro]

Hi Chris,

On 23-Jun-05, at 7:50 AM, Chris Smolinski wrote:

> I have both adapters. The advantage of the high speed unit is it  
> has a standard PC 9 pin serial port connector, with the extra  
> handshake lines.

Just to clarify - the Twin serial adapter includes the same DTR and  
RTS handshake lines as the high speed - it's just that the data and  
handshake lines are balanced in RS-422.

<http://www.brainboxes.com/standards/index.asp>

One of the ports on the Twin is able to emulate a Mac printer port.

> I believe the voltage levels are higher as well, +/-12 volts not  
> +/-5 volts like Mac style serial ports.

Part of the confusion is that both standards specify a voltage range  
rather than an absolute voltage.
In practice the RS-422 driver chip manufacturers usually provided  
+-6v for the differential lines...

<http://www.interfacebus.com/Design_Connector_RS422.html>
<http://www.rs485.com/rs485spec.html>

In any case with the correct cabling the Twin can be used with any  
device that the High Speed can - but the High Speed is not able to  
emulate an Apple printer port to work with some of the older Mac  
printers.


73 Don Agro VE3VRW

D o g   P a r k   S o f t w a r e   L t d .

email: dagro at dogparksoftware.com
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