Overview
How grid operators remotely monitor and control your installation through the Voltmasters EMS, and how Voltmasters delivers and certifies that link.
DSO RTU is the mechanism by which a distribution system operator (DSO) remotely monitors and controls a decentralized energy installation, through a Remote Terminal Unit (RTU) on site, in order to keep the electricity grid stable and within its physical limits.
Some grid operators have their own name for this mechanism. Fluvius, for example, calls it telecontrole. The general, operator-independent term used throughout this section is DSO RTU.
Voltmasters acts as the interface between the grid operator and your installation. The grid operator sends limits, control modes and, when needed, emergency stops; the Voltmasters EMS translates those signals into safe, immediate actions on the connected assets (PV, battery/ESS, EV charging, flexible loads) and continuously reports back what the installation is actually doing.
DSO RTU is increasingly a connection requirement for larger decentralized installations. The grid operator must be able to see and, if necessary, limit your injection or consumption. Voltmasters provides the certified link that makes this possible.
Our role and responsibility as an EMS
As an EMS, Voltmasters takes on a central and responsible role in the energy system:
Reliable data collection: we continuously and accurately read every connected asset and report consumption and injection per asset category. This data is the basis for all decisions at grid level; errors or delays are not acceptable.
Critical communication with remote monitoring: we maintain a stable, secure and protocol-correct link with the grid operator's systems. Data is validated and structured, protocol compatibility is guaranteed, and the real-time flow is continuously monitored.
Accurate execution of controls: when the grid operator requires an action (a limit, a control mode, an emergency stop), we execute it correctly and immediately on the installation.
Intelligent local decisions: alongside external control we keep optimizing locally (peak shaving, self-consumption, grid relief), often before central systems need to intervene.
Without a high-performance EMS, reliable remote monitoring and control at the asset level is simply not possible. Voltmasters consciously takes on this responsibility and has the knowledge and systems to execute it correctly, safely and efficiently.
What the grid operator can control
Through the DSO RTU connection the grid operator can, in real time:
Limit active power (P): cap injection (production) and/or consumption, both at the grid connection point and as a percentage of installed asset power.
Control reactive power (Q): switch between local and remote Q control and impose a reactive power band.
Trigger an emergency stop: stop production (injection) and/or stop consumption immediately.
Indicate a reason: every control carries a reason code (normal operation, grid congestion, or test).
In return, the EMS sends feedback (mirroring every command) and periodic measurements per asset category, so the grid operator can verify that the installation complies.
See How DSO RTU works for the full control model.
Two enforcement layers
A DSO RTU command is enforced on two independent levels:
Software: the EMS curtails the relevant assets in its control loop (setpoints to zero, batteries disconnected, loads off). This always happens.
Hardware (optional): for emergency stops, one or more relay outputs on a Moxa IO module can be driven to trigger a physical emergency stop on the installation, independent of the asset's own communication.
Supported grid operators
DSO RTU is operator-specific: each grid operator uses its own protocol, data model and certification process. The EMS hides this behind a single DSO RTU provider setting, so adding a new operator does not change how your assets are controlled.
See Supported grid operators for the current list and the roadmap.
How this section is organized
How DSO RTU works: the control model and data flow, end to end.
RTU connection: the network link between the grid operator's RTU and the EMS.
IO extension: the Moxa IO module as a device on the platform, its ports and how they are configured.
Installing the IO modules: where to place the Moxa modules and how to cable them across cabinets.
IO module emergency stop: wiring and configuring a Moxa output for a hardware emergency stop.
Commissioning & certification: how Voltmasters validates the link and assists with the grid operator's certification.
Supported grid operators: per-operator specifics and the roadmap.
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