Manipulating logistics network values not possible?

[VonFlaffenhausen]

I am designing a robot based mall and I want to set the amount of items that need to be created with constant combinators.
For instance when creating pumps, ill have combinator with "pump" 50. I then put that in an arithmetic combinator that does * x -1 so the output is -50.
I then hook up the inserter taking the items out of the assembler to be enabled as long as "pump is < 0"

This works when I wire it up. But what I want to do is feed the negative number in to the logistics network and then hook up the inserter to the logistics network as well. This does not work for me. I connect the arithmetic combinator to a power pole and the power pole to a roboport but I don't think the negative value is actually applied to the logistics network, its only on the wire.

So after some asking around, i understand that the logistics network is read only.
Why is this? It would be so nice if we could do the same things with the logistics network as we can with the wired network.

[DaveMcW]

You can put the logistics network on a wire, it is one of the options when you connect a roboport.

[BenSeidel]

Hi,
Yes the logistics network is read only. The wireless transmission of the logistics network is only there to allow you to act based on the current content of the network and not the required content of the network.

The only way that is possible to achieve what you want to achieve is to hook everything up via wires.