What's the relationship between the O2 sensor reading and the reading at pin 3 of the X11 diagnostic port?

I've seen the O2 sensor reading oscillate in a range between 0-1V as it should and read that the voltage at pin 3 should be somewhere between 6.8-7.2V. What happens in between?

Thanks,
Sixto
91 300SE
87 300SDL

Sixto:

I'm a diyer, so take this for what's it's worth:

Regarding your first question...the relationship.

The 2 sec. vascillation of voltage on the O2 sensor between .2v and .9v and the 6.6v - 7.2v reading on pin 3(50 per cent duty cycle) to me are somewhat synonymous.

Not sure I understand the tail end of your 2nd question.

The final post in the following thread might be of interest if you're trouble-shooting a mixture control issue.

O2 sensor failure and lambda testing