SparkFun Forums

[samltd]

Hi everyone
Does anybody know how to get this working:

The circuitry is an RS232 Optical Isolation which connect on Serial COM port.
http://chaokhun.kmitl.ac.th/~kswichit/R ... Rs232.html

How can I make an adapter to get this circuitry to work on USB?
Thanks

[Kuroi Kenjin]

You can't. The problem is that USB is a half duplex differential protocol. That is the host can driver the differential bus (3.3,0 or 0,3.3 on the lines), OR (exclusively) the device can drive the bus.

Just maybe, you can use 2 RS-232 to USB converters put the optos between them and power them off of one device. This will lead to a huge loss in preformance and you'd be just better off communicating with RS-232.

There is a possibility of using a signal transformer, as in Ethernet. Although I don't know how adversly that would affect the preformance and whether that would work at all.