On Friday, August 22, 2003, at 07:25 AM, Stephen Quinn Barncard wrote:
Rather than destroy a cable or mess with those horrible mini-dins, I would use a mini-din to DB-9 adaptor (still available), then wire a DB-9 Female (or male, i forgot).
Good idea. I didn't realize they were still around.
Another idea is to build that adaptor with an old cable. I currently make my adaptors adapt to the DB-9 and then use null modems and extenders and loop-backs on that, but I'm currently partially DB-25. I never did get on the RJ-45 craze for RS-232. (Notice that I never mess with "those horrible mini-dins"--was so even before the hands got rusty. Besides, they are hard to find.)
One potential problem is the handshaking. The mac has only one in and one out and I'm not sure how they work. I'd make one with none and one with those connected to RTS and CTS.
I have a power supply which a Mac cannot talk to. It needs a strong RTS to power the optical isolation circuit. I love the idea of isolation. The signal ground and the signals are isolated. But they got cheap and powered it from the RTS. The data that came with it indicates that the Mac output handshake line will not work.
In general, RS422 is not RS232 and any setup might have problems.
BTW, there is no standard (that I know of) for RS422 DB9, the adaptor I'm describing above is for emulating RS232 on DB9.
It is possible to get 422 to 232 adaptors which are electronic level converters and sometimes isolated. This might allow one to exploit the distances one expects from 422.
And while I'm babbling, I think it is possible to use mac in a two-pair RS-485 situation in some configurations.
Dar Scott
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http://www.swcp.com/dsc/
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