Compatibility
Siemens S7-300, S7-400, S7-1200 and S7-1500 driver for SCADA
The siemens-s7 driver connects Nexus to Siemens controllers over S7 on ISO-on-TCP. It is included in every licence.
What it connects to
One driver, siemens-s7, covers four families: S7-300, S7-400, S7-1200 and S7-1500. A setting called plcType picks the family, with the values s7-300, s7-400, s7-1200 and s7-1500.
Setup in brief
rack and slot locate the processor. A 1200 or 1500 is normally rack 0, slot 1. For a 300 or 400 the answer depends on how the chassis is populated. pduSize caps the negotiated PDU if the processor needs it held down.
Tags use absolute addresses such as DB1.DBD12. On a 1200 or 1500 that means allowing PUT/GET access on the CPU and turning off optimized block access on the data blocks Nexus reads.
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.
Everything above is in the manual under Devices and drivers, Siemens S7.
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.
Limits
S7-200, S7-200 SMART and LOGO! are not native drivers. Some of them offer Modbus TCP, so check your model and firmware. If yours does, the Modbus driver reads it.
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.