No measurement is lost, even if the internet goes down or the server restarts. The SQLite queue retains data for up to 14 days; once the connection is restored, data is transmitted automatically and cannot be deleted without ACK confirmation.
In cloud-based systems, real-time data is lost when the connection drops, creating a critical gap for billing and alarms.
No data can be received during backend updates or maintenance; this period is excluded from energy analysis.
Seasonal facilities or remote sites may go without a connection for weeks.
If the same measurement is written twice during retransmission, calculations break and alarms trigger incorrectly.
The Field Agent writes every measurement to the local SQLite queue first. It is not removed from the queue until it has been written to the server.
The server confirms receipt of each measurement with an MQTT ACK message. A queue entry does not transition SENT→ACKED until the ACK arrives.
With a 5 GiB SQLite database capacity, all data is preserved even if the site stays offline for 14 days.
Once the connection is reestablished, accumulated data is transmitted automatically in chronological order, with no manual intervention required.
A UNIQUE(cihaz_id, okuma_zamani) constraint in the database: if the same measurement is attempted twice, it is not dropped but IGNOREd.
A warning alarm at 80% capacity before the 14 days fill up — the site's connection problem is detected in advance.
Most sites in Turkey stay offline for at most a weekend plus public holidays. 14 days provides a safe buffer for both seasonal shutdowns and unexpected communication failures. The maximum buffer duration is configurable.
The queue entry remains in the PENDING state. When the Field Agent reestablishes the connection, it resends all PENDING records. Even if a record is sent to the server multiple times, the UNIQUE constraint in the database prevents duplication.
Argus EMS uses MQTT QoS 1 (at-least-once delivery). In addition, the application-layer ACK state machine forms a second layer of security in cases where even QoS 0 would be unreliable.
The queue never drops data (DROP). When capacity is reached, a QueueFullError is thrown and an alarm is generated. This design is intentional: it prefers to detect the problem early rather than delete data.
| Local Storage | SQLite — 5 GiB cap (≈14 days) |
| Protocol | MQTT QoS 1 + application-layer ACK |
| State Machine | PENDING → SENT → ACKED → deleted |
| Duplication Protection | UNIQUE(cihaz_id, okuma_zamani) DO NOTHING |
| Queue Full Alarm | Warning at 80% capacity, QueueFullError at 100% |
No measurement is lost, no matter the internet outage or server maintenance.
Request a Demo → info@nevacontrol.com