question

The start signal cable that comes from the CCGX relay could be connected in series through a second relay of the Quattro. With the Programmable-Relay-Assistant switch of the relay if AC In 2 is active. Then the start signal will not get through to the generator if AC In 2 is active.

The answer is to use AC In 1 for shore power and AC In 2 for generator.

AC In 1 has priority over AC In 2. Which you connect to grid and generator depends on grid reliability/robustness.

Victron recommends AC In 1 for generator in "weak grid" situations, where the grid isn't always capable of supplying the load. In this case, the Quatro will supply the load from the batteries, then start the generator when low state of charge or high load thresholds are reached.

However if the grid can supply the load, there's no reason to call on the generator to take over and it makes sense to give grid priority over generator.

The rest of the solution is to turn on "Do not run generator when AC1 is in use". That setting is in the generator start/stop conditions.

There's more about setting up for generator control here:

https://www.victronenergy.com/live/ccgx:generator_start_stop

BTW, this only works for Quatro inverter/chargers since Multi only has one input. In the case of a Multi, the switch between grid and generator must be made up stream of the Multi and CCGX has no way of knowing which source is active or present.

This isn't so much an answer to the original question as a proposal to Victron for a bug correction ... not sure where to do this, but maybe someone will pick up or advise.

The Quattro on my ship is connected AC1 <- genset, AC2 <- grid. This is the Victron recommended arrangement for installations where grid power is not the primary / reliable power source and I think that installations on many cruising vessels will be like this.

In Venus OS, the mains input types are easily configured in the GUI and these configuration changes are applied through most of the system and exported to the VRM.

PROBLEM

The Venus mains input configuration is ignored by the Generator Auto-start feature which assumes grid input on AC1.

The configuration option "Do not run generator when AC1 is in use" is predicated on the false assumption that AC1 is always grid input.

PROPOSAL

Change the generator auto start facility so that it offers and responds to the selection of AC1 or AC2 as a generator start override, or, better, acknowledges the Venus OS configuration for grid input.

The revised prompt would then be something like "Do not run generator when grid power is available".

See my old post regarding this:
https://community.victronenergy.com/idea/60050/quattro-ac-connections-suggested-manual-update-1.html