ddmdavid01:
Hey, I am having the same problem right now. I have a mega and a uno and I have been able to communicate to each other for a few month, but now they don't work at all. I tried the 10 uF capacitor and it still does not work. Can someone tell me what happened?
You need to post the programs you are using. Also post a sample of the output from both programs?
When you say you have "been able to communicate to each other for a few month, but now they don't work at all" does that meant that the programs have been on both Arduinos throughout that period without EVER being changed, And throughout that period NONE of the connections was disturbed. Then for no reason at all one day they could not communicate?