Good Evening to all,

I’m new in this forum but I’m a Marklin guy since my birth, I need your help with an issue, I have a CS2 that worked fine with the L88 and the S88DC that is connected to the L88 through an RG45, from last week the dots happeared red in the CS2 and she lost contact with the S88dc, I tested the items with a CS3 and all is working fine, but when I connect to my CS2 she doesn’t recognise the S88dc, can anyone help with this?

Assuming you have got power to the L88...

I would focus on the L88s settings in the CS2 and make sure you have the "bus length" set to the number of S88s on the bus.

If a sensor is red it is generally an indication that , at startup, the CS3 could not find the "ports host".
i.e. the L88 with the bus length set as needed to be able to scan for the port.

This behaviour It is not uncommon for the CS2 (CS3 is a lot better).
And once the CS2 and all devices are up, you can try power cycling just the L88 (wait 30 seconds)

The configuration for the L88 is done within the CS2 , not the L88.
And there appears to be some "housekeeping" that occurs if the CS2 goes through 2/3 restarts without seeing a previously configured L88.
When it does next see it, it treats it as new, i.e. L88 to 16 port mode (looses keyboard mode if set) and Bus lengths to 0