(relatively) simple circuit for dynamic quality

[isambard_brunel]

I would like to build pipes with quality selected dynamically based on the input. Ideally with direct insertion from a recycler. I've tried various permutations for some time now and can't figure out how to do it with my current circuit skill. The fundamental issue with the simple method (ie no memory cells) is that if the set recipe signal is changed from quality 1 to quality 2 with quality 1 iron in the crafting inventory of an assembler, the quality 1 iron is moved to the output inventory of the assembler, which then deadlocks until the quality 1 iron is removed. This could be removed with a filtered inserter set to everything < 0, but this then precludes sending read content signals from the assembler which is necessary to set the recipe.

any ideas? the simpler the better

[Tertius]

... which then deadlocks until the quality 1 iron is removed. This could be removed with a filtered inserter set to everything < 0, but this then precludes sending read content signals from the assembler which is necessary to set the recipe.

Difficult to understand what you mean with "set to everything < 0" since a machine can never contain less than zero items, but this seems your point, so I don't understand the issue in the first place.

In general, if you connect a machine to the circuit network, you're able to make it send its content (always both input slots and output slots), send the items currently in the current production step, send ingredients required by the current recipe. If you activate reading content and reading ingredients, you're unable to separate the ingredient signals from the content signals. It's both merged. If these signals are important for your setup, you need to create a setup where you either read ingredients and not content or read content and not ingredients, but not both.

As far as I see, you don't need to read the machine content. Read ingredient info but not content. Use unfiltered inserters to remove any item from the machine and determine what has been removed by either reading hand content of the inserter or read the chest where the inserter puts the removed items.