On Mon, 2010-03-15 at 09:33 +0100, Bas Mevissen wrote: > On Sat, 2010-03-13 at 18:31 +0100, Joerg Albert wrote: > > I use a Prolific PL2303 serial USB adapter which works fine with other > > hardware. Someone else? > > Do you have access to an oscilloscope? It might be that the signal level > or signal shape is not perfect. I've seen mixed results with various > serial to USB adapters too. > > You can also try to replace the net adapter of the board. These adapters > tend to age and perform worse.
The PL2303 data sheet says "RS232-like" in about a million places where one may rather see actual "RS232". I suspect a PL2303 running off 5V USB supply voltage may only pump -10v/10v signal levels (similar to some Maxim chips which have a simple doubling charge pump), and some devices may not do too well at the 2v difference, even though the RS232 spec I believe states a range between 10 and 12 as within the limits. Either way, it could be marginal depending on the other transceivers involved. The Maxim chips will work down to -9v/9v or so and seem to be some of the most tolerant of voltage or dirty signal - so the other suggestion about double shifting via cascaded Maxim chips is probably a great way to recondition the signal if the PL2303 "RS232-like" output is not quite "RS232-enough" for your equipment. _______________________________________________ openwrt-devel mailing list [email protected] https://lists.openwrt.org/mailman/listinfo/openwrt-devel
