IFD5xx/4xx Data Link Data Not Received
This is an Advisory (Cyan) CAS message indicating that "X" amount of time has lapsed since a given weather product has been received.
For example, let's look at SIGMETs.
From the specifications: "The Broadcast SIGMETs product shall timeout if no data of this product type has been received within 15 minutes after IFD data link message suppression period."
So, the way we handle this is if there are no SIGMETs received within that 15 minute period, we issue the CAS message to let the PIC know.
Now for the tricky part of this. What if it's a beautiful day, and the ground stations are not reporting any SIGMETs, because there are none to report? As far as the ADS-B weather receiver and the IFD are concerned, this looks exactly the same. If the ground station is not sending any data, because there is no data to send, the IFD will alert you that there is no data received.
If you see this message, the recommended action is to review the data link status page here: