On Wed, 6 Jun 2012, Joel Wiramu Pauling wrote:
Possibly your laptop or cable is killing it. Rs323 cabling and ports use quite high voltage for signalling in comparison to say USB or ethernet... If the chip set of the Linux box is borked you may be frying the port.
Possible, but only if console ports are themselves sub-spec. Generating enough voltage to fry a to-spec RS232 port is beyond the wildest dreams of most PCs; they simply don't have the electronics to generate the voltages needed to cause damage. RS232 requires that inputs tolerate at least ±25 V, but sense high/low transitions somewhere in ±3 V. (And outputs should likewise be immune to indefinite short-circuit to any voltage in ±25 V.) A "nice" RS232 receiver will operate with threshold at around +2 V (thus being being compatible with RS422 driving at 0/+5 V), but won't blow even with any pin connected to ±47 V (thus being safe for telco work / abuse). Good luck finding a new device that'll meet that improved spec... -Martin