I am eager to connect my EZ-B to my Roomba, but don't want to risk frying the board. The EZ-B tutorial states:

*Note Before Connecting To EZ-B:: Check the signal wire (white wire) with a volt meter and ensure you have zero volts from the Roomba. If you see voltage, you're connected to the wrong port. If you apply current to the the EZ-B from the Roomba, you will damage the D0 port and will require a chip replacement.

Here is the problem:

If I attach my multimeter directly to the port on the Roomba and check the voltage by connecting the negative black lead to the hole for pin #7 (GND) and the positive red lead to the hole for pin #3 (RXD), or any other hole in the port, I read voltage.

Holes #1 & #2 have a higher voltage (14 - 16 volts) because they are unregulated. Hole #3, 4 & 5 have 4.5 volts.

I have read on other websites - "Measure the DD, TX, and RX pins with a voltmeter. They should be either 0 or five volts."

Apparently my RX is not zero but closer to 5 volts. Does this mean that I can't use the EZ-B with this Roomba?

Can someone let me know if this is normal or not? If the voltage coming out of RXD from the Roomba absolutely needs to read zero volts, how can I remedy the situation?