Compatibility
DNP3 driver for SCADA: polling outstations from Nexus
The dnp3 driver lets Nexus act as a DNP3 master and poll outstations. Where an outstation timestamps its own events, Nexus keeps that time.
What it connects to
DNP3 outstations: the remote devices that hold the points. The protocol is common in electric, water and other utility telemetry, where a master polls many outstations over links that can be slow or unreliable. In Raylux, Nexus is the master and each outstation is a device entry using the dnp3 driver.
Source timestamps
DNP3 outstations can supply their own sequence-of-events timestamps. Where one does, Nexus records that timestamp as the source time rather than the moment it received the value. For alarms and history that matters: a value that changed earlier keeps the time the outstation gave it.
Setup in brief
outstationAddress and masterAddress are the DNP3 link addresses, the first for the outstation and the second for Nexus. eventPollEveryNCycles controls how often an event poll is issued relative to ordinary integrity polls. maxObjectsPerRequest caps request size for outstations that dislike large ones.
Like every Nexus device, it carries a name, an endpoint, a port, a fallback pollRateMs, a timeoutMs and a reconnectDelayMs. The name is what tags refer to, so rename a device in the configuration interface rather than by hand in the file, or its tag bindings break. A device holds no address list. It polls exactly the tags bound to it, so adding a tag in Studio starts it scanning without editing the device or restarting Nexus.
These settings are in the manual under Devices and drivers, DNP3. The quickest check is to point the trial at your outstation and watch the device card.
Scan rates and dropped links
Scan rate comes from the tag group, not the device. A group is direct (a fixed rate), leased (quick while something is watching the tag, slow otherwise) or driven (quick while an expression is true). A fresh gateway ships with default-fast at 250 ms, default-slow at 5000 ms and default-historical at 10 s. A tag goes Stale after its rate times staleMultiplier passes without an update, and returns to Good once it is being read again. A rate faster than the device can answer does not bring data sooner; the poll just falls behind.
A device that stops answering is marked disconnected, and its tags follow the quality rules instead of freezing at their last value. Writes forwarded to a device that has since dropped are not silently discarded. The device list in the Nexus configuration section shows each device’s state, with the reason for a failure in the tooltip. The troubleshooting page covers the usual causes.
Licence and trial
Every driver is included in the base licence, which lists at $995. No driver is sold separately, and there is no per-protocol or per-gateway driver charge.
The free trial runs for two hours with every driver unlocked, and you can restart it as often as you like. Point it at the controller on your bench and read a tag before you decide anything.
Related drivers
Next step
Read a tag off your own PLC.
The trial is two hours with every driver unlocked, and restartable as often as you like. Point it at the controller on your bench before you decide anything.