PCF8574 datasheet gives an exact pattern. I forgot to check it. Sry. What I get is the same as what my Nano sends.
Here one can see the I2C address and array of bits.
One thing more.
The author of this sketch recommends an ISO154x IC. But which one? ISO1541 or ISO1540? If in my case I use this setup from above?
There are differences between them But, here, I can by only ISO1541.