Tune LoRaWAN receive windows
A Sigfox device listens once, about twenty seconds after it asks. A LoRaWAN Class A device listens twice, and only briefly, right after every uplink: the first window (RX1) opens after the RX1 delay, the second (RX2) one second later. Between uplinks it is deaf.
That delay is the whole story of whether the Center can answer a LoRaWAN device in the same exchange.
Why the RX1 delay matters
When a rule responds with a downlink on a LoRaWAN source, the Center computes the frame on the uplink and pushes it to the network server, which queues it for the device. The network server sends it in this uplink's window only if it has the frame before RX1 opens.
| RX1 delay | What happens |
|---|---|
| 1 s (the LoRaWAN default) | The push never makes it. The frame waits for the next uplink. |
| 5 s (The Things Stack's Europe plan) | A rule with a constant, a field or a fast encoder answers in the same window. |
| up to 15 s | More room for a slow codec or a bridged sink. Costs the device a little battery per uplink. |
So for a device that must react to what it just sent — a valve that closes when the meter reports unpaid — set the RX1 delay to five seconds or more.
Where to set it
Every LoRaWAN device on the Center gets its MAC settings from four layers, later wins:
Each field is either inherit — the placeholder tells you the value that applies and which layer it comes from — or a value of its own. Leave everything on inherit and the network server's defaults apply.
Two families of values
The form's headline RX1 delay is the negotiated one: what the network server asks the device to use once it has joined. Behind Show boot values are the device's factory settings — what it uses before anything is negotiated. Unless a datasheet says otherwise, change the negotiated values and leave the boot values alone.
The other sections follow the same split: receive windows, adaptive data rate (dynamic, static or off), regulatory limits, frame counters, status reports, Class B / C timing, factory channels, and a Schedule downlinks switch that pauses every downlink to the device when off.
Apply, and watch for drift
Settings reach the network server when the device is registered from its page. For a device already registered, the Receive windows & MAC block has Preview settings → Apply settings: a single request to the Network Server, nothing else touched.
With live reads on, the same block shows what the network server actually holds. In sync means the Center's effective settings match it; a drift badge lists the fields that differ — a value someone changed in the LNS console, or a layer edited since the last apply.