When the Dosing Unit Gen1 was connected to an S port on Profilux 3ex, communication light was ON.

I bought a PLM-2L4S interface expansion card and I install it on my Expansion Box 1.

Then I connect the Dosing Unit Gen1 to this expansion card.

Dosing Unit is working fine but communication led is OFF.

If I reconnect the Dosing Unit to my Profilux 3ex, communication led is ON. (This means that the led is working fine).

It seems like the verification of the communication (led ON) can only happen when the Dosing Unit is directly connected to Profilux.

Is this the case or is there something I can try?