Thank you for your answer 8-)

In the mean time, I found a solution, that does not require to read what the machine is doing. Let me explain...

I want to manage manufacturing remotely, so I can sit in orbit and tell the machines on the planet, what to produce.
1. in orbit I have a constant ...

I am trying to make a setup, where I send a recipe to an array of assemblers and as soon as an assembler has accepted a recipe, it should no longer listen for new recipes. I thought I could simply use a decider by reading the set recipe from the assembler, but it does not look like an assembler ...