John Nall wrote: > Well, if replies go both ways, then I will choose the safer route. > :-) Even better than being once bitten is listening to someone who has > been bit before. I hot plug RS-232 frequently, surely 1000s of times by now. I have never once found that to damage anything when both ends were proper devices. RS-232 is deliberatly specified to handle a decent voltage range, be short circuit proof, etc. The only problem I can see is if the two devices are floating with respect to each other and static electricity builds up between them. Even then that should be OK if the shields are properly connected because they would make contact first. I always make sure the sheild is connected to ground on stuff I build, but you could have a cable that doesn't wire the shield accross. ***************************************************************** Embed Inc, embedded system specialists in Littleton Massachusetts (978) 742-9014, http://www.embedinc.com -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist