RE: Reliable messages with long timeout

Batov — Tue, 25 Feb 2020 10:49:01 GMT

I am using nrf_ble_scan_start for scan BLE beacons around server side device. It takes more time than expected for STATUS message with ack.

I am using access_reliable_t.timeout field too (at light switch client example you copy MODEL_ACKNOWLEDGED_TRANSACTION_TIMEOUT there). Look at my first code sample at 17 line. But calculate_interval() ignores it because calculated interval (based on ACCESS_RELIABLE_INTERVAL_DEFAULT and the TTL) less than timeout.

Change ACCESS_RELIABLE_INTERVAL_DEFAULT will help me, but I want to avoid modiging network stack.

Skipping access_reliable is suitable case for me.

Then again, I can add duplicate messages barrier on server model side.

Thanks a lot for you answer. It's very useful for me. You prove my points!

RE: Reliable messages with long timeout

Hung Bui — Mon, 24 Feb 2020 14:50:32 GMT

Hi Batov,

Could you explain a little bit more on "scanning at server is not so fast operation." ? Are you limiting the scanning window ?

You can configure the reliable message timeout by defining MODEL_ACKNOWLEDGED_TRANSACTION_TIMEOUT (usually inside nrf_mesh_config_app.h) . This is the valued used when calling access_model_reliable_publish() in our light switch client example.

The access_reliable library automatically schedule a retransmission for reliable message with the interval calculated in calculate_interval(). It's based on ACCESS_RELIABLE_INTERVAL_DEFAULT and the TTL value.

You can adjust the timeout and the interval to fit better with your network configuration.

Another option is to use the access layer directly and skip the access_reliable.c library. This way you can choose what you want to do with the reliable message.