(There were two posts on this, I deleted the other one).
> when I run the job the nozzles don't change automatically.
You need to set up the nozzle change and enable the automatic change (lower right) in the nozzle setup page. The software will then use the nozzle specified in job data table.
> when one PCB assembly is finished and second is placed the nozzle goes to pick up the component from second hole and trips.
In other words: On first try, the machine picks up one (and only one) part from a tape. On next board, it goes to second part, tries to pick it up, the switch triggers and it fails. Did I understand this correctly?
First, you need to have the pickup tube mechanically set correctly. When you push the tube up from the nozzle tip, it should go up, triggering the switch. Then, the bottom collar should go against the lower tubing. Only after this, would the spring in the nozzle adapter start to compress. When you let go, the tube should drop fully down under its own weight, at all rotational positions. Then, your nozzle height should be calibrated and your pickup depth correctly set, please see
https://www.liteplacer.com/calibrate-needle-height/.
With these set, the system should work like this: On first try, the software measures the pickup Z level, and places the measurement result to the tape data. This is done at full down value, triggering the switch. Next time this tape is used, the measured Z value and the nozzle height calibration values are used to determine the correct Z level for pickup. The switch is active to guard against error conditions. (The z motor is strong enough to cause damage if something goes off.) When setting things up, it is possible that the table gets wrong or old values in it; for this, there are buttons to reset the Zs. Also, the the nozzle height calibration routine asks to reset Zs when it is finished. In most cases, you need to answer yes.
I hope these help. I f you still have issues, maybe you can give some details of what goes wrong.