I want to send a MAC command via ChirpStack. I tried sending it through the queue interface, but I couldn’t choose FPort = 0. Is there any other solution to send the MAC command from ChirpStack to the LoRa device?
This is not a normal thing and is not supported via the usual methods of sending downlinks. What’s your usecase?
You can’t.
But
a. You can receive a MAC command (Rx Parameters) with the join.
b. or if you jump the framecounter (you will receive NbTrans MAC command > 1),
c. or you can configure in device profile to receive a Device-status request frequency (req/day)
d. or close to a GW with SF > 7 and ADR enabled on your device you will receive an ADR command.
e. or issue TimeReq or LinkCheck from device.
ATTENTION: all those are suggested for testing, not for production.
There is seldom a reason to send downlink MAC commands.
The MAC commands should be for internal LoRaWAN protocol only.
Most of the time, we only need downlink commands to control LoRaWAN devices (with FPort > 0).