LR1110 modem driver ALC synch

Hi everybody,
I have problems with implementig application layer clock (ALC) synchronization with LR1110 using modem drivers. I am able to joining the network and than active the ALC service on the port 202. I see on the gateway log uplink packet on port 202 and a downlink immediatly after this, but at the LR1110 i don’t receive anythong and it does not fire an interrupt of clock synchronizations as mentioned in the manual. The same happens with messages on port 199 (DM), the device doesn’t fire any interrupt. Instead if I schedule a downlink with my custom data I receive it, LR1110 fires an interrupt and I can read data.
What can be the problem?
Thanks in advance


Could you please share with is the downlinks generated by the ALC Sync service on port 202 and the Device & Application Services server on port 199?

Hi, here you can see the uplink and the downlink generated

After the join, I receive three LR1110_MODEM_LORAWAN_EVENT_NEW_LINK_ADR, and in the log I see three uplinks on port 202 every 128s, but no downlink seems occurs after it and the device never get synchronized to the network (the function gettime() returns always zero value instead of gps time)


The downlink you are receiving is a MAC command related to network parameters, not ALC Sync.
ALC is for Application Layer Clock synchronization, which mean that you need to provide an application server answering to the device ALCSync requests. Do you have one?
Otherwise you can use as ALCSync server, here is the service description