This quide is an example of how to use compute blocks, sort minecarts and start with designing an intelligent delivery/distribution network.

I hope that the picture explains everything.

The idea was to:
1. Move minecarts only when needed, so they go to factories only when particular silos needs to be resupplied. In general minecarts wait on rail stops just before silos and wait to be emptied.
Note that the inventory sensor is pointed to the rail stop, not to the silos. It has to watch the inventory of the minecart waiting at the rail stop.
2. Resupply silos as soon as possible enabling it to be emptied in bursts by incoming 3-7 empty minecarts on the other side, even one after another. This is achieved by designing a waiting line for full minecarts just before silos.
3. Have a loop just before factories so minecarts that are not full return and try to resupply as soon as possible. This is achieved by having two tracks. One for minecarts that are full and ready to be routed to proper silos and the other track for minecarts that are not full and need to be routed back to factories.
4. Most important point - to have fun with compute blocks! :)

I use just 2 minecarts for every item, but of course I could go even with more.
Every inventory sensor is connected to number block (just to see the number) and also to math block that compares the received signal with its value. Then the math block is connected to particular blocker.

I learned a lot about compute blocks from this gamepedia guide:
https://factorytown.gamepedia.com/Logic_Blocks_Guide

Have fun!