I believe it means that the remote device, ie, the LM-3S-G, was busy and after repeated attempts the HC wasn't able to initiate a download with the LM.
From memory I've had this a couple of times before and I think there's a couple of possible reasons.
- Trying to do something with the LM before it's finished processing something else, ie, trying to download to the LM while it's still processing a firmware upgrade.
- Trying to do something like downloading while the LM is being controlled, ie speed step isn't zero.
If neither of those were the cause then something else was at play but it'd shouldn't be happening constantly.
- Tim