The LED should be on when there is a board powered up in the slot associated to that COM port and USB. For example the S3 chassis has three COM ports one for each slot. In contrast the S4 only has two representing the two fabric slots marked with a red band (slot 2 and 3).
thanks for your reply. The reason for my question; I've a S8-Chassis with 3 installed fabric-modules (slot 4,5,6). But only the LEDs on the COM/USB-ports for slot 4 and 5 are on. LED for slot 6 is off. Module 6 is active and working (more or less). It has some strange effects on 2 or 4 ports. The questions is, can this even indicate an issue with the card?