Mesa 5i25+7i85S+7i66

Both, you need at least:

1. A proper connection between the 7I66 and the 7I85S
2. Correct firmware on the 5I25 (5I25_7i85sx2.bit)
3. LinuxCNC (or at least the driver and read/write thread) running

Before the red light will go out (and the green light will blink)

I did everything but pnccofige I don't see 7i66. What should I do to 7i66 appeared in pnccofige? Thanks.

Yes pncconf has no direct support for the 7I66 but you can make a generic 7i85sx2 configuration
and add the 7I66 I/O to the hal file

If you make a generic 7I85sx2 configuration and start it, you can list all the 7I66 pins with:


and then use the 7i66pins.txt file as a "donor" file for copy pasting into the hal file and
connecting them to the desired LinuxCNC pins/signals.

I so and wanted to do as you wrote, but I cannot see this board 7i66.
I can't turn off this red light on 7i66. (
Do I need to install the driver "sserial" for 7i66 or is it already preinstalled?
I tried to install this driver, but my command fails "sudo ./updatess 7i66 5i25 2".

Did you verify these three things:

1. A proper connection between the 7I66 and the 7I85S
2. Correct firmware on the 5I25 (5I25_7i85sx2.bit)
3. LinuxCNC (or at least the driver and read/write thread) running

To which I would add

4. 5V power to the 7I85S (yellow light on)

There is no separate driver for sserial, its built into hostmot2
There is no need to update anything on the 7I66

Does the serial port pin numbering on the 7i66 start at the top or bottom?