What is the payload size according to region and data rate?

[Takahashi (Carlos Takahashi)]

I am developing an application with the RAK3172 module in Brazil, using the AU915 region.
I configured DR = 2, ADR = 0 and tried to send:

api.lorawan.send(length, payload, fport, confirm, retry)
length = 50 bytes;
payload[50] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
fport = 21;
confirm = true;
retry = 3;

I’m getting “false” return.
I verified in the LORAWAN 1.0.3 reginal specification that for DR = 2, the maximum size is 51 bytes, as shown in the figure below.
I also did a test, reducing the payload size to 10 bytes and in this case it worked.

Please could you tell me why this error is happening?

Best Regards.

[beegee (Bernd Giesecke)]

The UplinkDwellTime, which is active by default, reduces the payload size to 11/19 bytes at DR2.

To get the higher payload at DR2, you have to disable UplinkDwellTime on your LoRaWAN server.

[Takahashi (Carlos Takahashi)]

@beegee

UplinkDwellTime

Hello Bernd.

Many thanks for the reply.
Should disabling UplinkDwellTime be done by my LORAWAN service provider?
Is there nothing to be done on the RAK3172 side?

Best Regards.

[beegee (Bernd Giesecke)]

Yes, it should be disabled on the LNS side and on the RAK3172 try with AT+DCS=0.
But some regions have duty cycle active always (like EU868) and you cannot disable it on the node side.

[Takahashi (Carlos Takahashi)]

Understood Bernd.
Thank you very much.