Application example for an ORES RTU, inverter control, a main and back-up switch, and additional digital inputs and relays.
This application note extends the ORES setup guide for an installation with an ORES RTU, inverter control, a decoupling cabinet and a separate back-up circuit breaker, as found in a Phoenix Pilot style arrangement. Follow the original guide to configure ORES External Control; use this page to design the additional contact interface.
The available digital inputs and potential-free relay outputs of the Sunlight Group EMS are used for this interface. Digital inputs read external contacts; relay outputs switch the designated control circuits. When the available channels are insufficient, add an Ethernet I/O module such as the dS1242 or dS3484 and configure the additional channels.
P means the main switch, BU the back-up switch, DI a digital input and RO a potential-free relay output. The diagrams below describe functions and signal directions. Terminal numbering, voltages and contact states follow the project's electrical drawings.
Select the diagram to view it at full size.
The example allocates 7 DI and 3 relay outputs. DI and RO numbers identify logical functions; map them to the available controller and extension-module channels. Dashed connections represent the additional project-configured cabinet commands. The standard ORES interface uses the RTU watchdog input and controller availability relay; the protection circuits retain their independent function.
The controller receives ORES power commands through the RTU interface and applies the corresponding regulation to the connected inverters. In an arrangement containing a Phoenix Pilot box, this is the inverter communication and power-control function. The RTU connection uses a dedicated RS485 interface; the inverter communication uses another interface. Keep a single controller responsible for writing the inverter control setpoints.
This diagram shows the 7 DI / 3 RO example detailed below. An Ethernet I/O module exchanges its channel states with the controller over Modbus TCP. Existing controller I/O and extension-module I/O are combined in the channel allocation.
The standard ORES wizard assigns one RTU watchdog input and one controller availability relay. The two switch-command inputs, switch-position inputs and two cabinet command outputs are additional project functions. Their signal mapping, interlocks and operating sequence must be configured for the installation; adding the ORES external signal does not automatically create this cabinet logic.
The voltage/frequency protection relay, trip circuits, interlocks and back-up protection retain their electrical protection function. The controller handles power regulation and the configured contact interface. Its presence does not replace the protection relay or establish the protection timing of the installation.
Select the diagram to view it at full size. The grouping shows signal functions, not electrical bridges.
The cable cores carry several different functions: commands, actual switch positions, protection status and trip-coil power. A terminal pair is not two independent commands, and a six-terminal connector is not necessarily six inputs.
| Signal designation | Function | Terminal and I/O allocation |
|---|---|---|
| WD Relais | Availability contact of the protection relay | One contact circuit, normally represented by two terminals. This is distinct from the controller's Wd PLC signal. |
| Trip 1 / Trip 2 | Separate protection trip circuits | Two contact circuits, normally four terminals in total. Retain their individual functions in the protection design. |
| Status P / P NO / P NC | Main-switch common and complementary auxiliary contacts | Three terminals; two DI when both open and closed indications are monitored. |
| Status BU / BU NO / BU NC | Back-up-switch common and complementary auxiliary contacts | Three terminals; two DI when both indications are monitored. |
| MX 1+ / MX 1- | Supply circuit for the back-up trip coil | Two coil terminals; these do not count as two digital inputs. |
These groups account for 14 terminals: 6 protection-contact terminals + 6 position-contact terminals + 2 coil terminals. They do not represent 14 controller commands. Count the actual signals that the controller must read or switch, then allocate the corresponding channels.
Reading both auxiliary contacts provides separate open and closed indications. Define which contact combinations are valid and how long a transition may take. A relay command proves that a command was issued; the switch auxiliary contacts provide the actual position feedback.
The following allocation assumes that both main and back-up switch positions are read by the controller, both RTU switch commands enter the controller, and the controller has one independent command output for each switch circuit.
| Function | DI | RO | Assignment |
|---|---|---|---|
| Watchdog RTU | 1 | 0 | RTU contact to the watchdog input selected in the ORES wizard |
| Wd PLC / controller availability | 0 | 1 | Controller relay contact to the RTU availability input |
| P open and P closed | 2 | 0 | Two main-switch auxiliary indications |
| BU open and BU closed | 2 | 0 | Two back-up-switch auxiliary indications |
| Switch P and Switch BU | 2 | 0 | Two separate RTU command contacts |
| P and BU command circuits | 0 | 2 | Two independent, project-configured relay outputs |
| Example total | 7 | 3 | Excludes additional alarms and spare capacity |
| Optional Err V and Err Fq monitoring | +2 | 0 | Separate voltage and frequency fault indications, if provided |
With the two optional fault indications, the allocation becomes 9 DI / 3 RO. This is the channel budget for this example, not a universal ORES requirement. The standard ORES connection remains 1 DI / 1 RO plus dedicated RS485. If the RTU commands act directly on the cabinet and the controller does not process them, those two command inputs and two command outputs are not part of the controller's allocation.
This budget assumes any additional hardwired status reporting to the RTU is provided through suitable auxiliary contacts or isolated interfaces. If the controller must reproduce P/BU positions or fault indications through separate relay outputs to the RTU, add those outputs individually. Do not assume that one physical contact can be shared between two independently supplied input circuits.
Subtract the unused, electrically suitable controller channels from the budget before selecting the extension. Reserve the ORES watchdog input and availability relay as part of that calculation.
| Module | Potential-free changeover relays | Shared digital I/O configured as inputs | Interface / supply |
|---|---|---|---|
| dS1242 | 2 | Up to 4 | Ethernet Modbus TCP / 12 V DC |
| dS3484 | 4 | Up to 8 | Ethernet Modbus TCP / 12 V DC |
For the 7 DI / 3 RO example:
The shared digital I/O channels can also operate as NPN outputs. An NPN output is not a potential-free relay contact, and using a shared channel as an output reduces the available input count. Use an electrically suitable interposing relay where a transistor output must switch an isolated contact circuit.
Follow the dS1242 Ethernet relay module guide for the module connection and commissioning workflow. Register each required input and relay channel in the controller, using the physical channel count of the installed model. The dS1242 has two relay channels and four digital I/O channels; a longer channel list in a shared device driver does not add physical channels.
The standard ORES driver energises the controller availability relay during operation; this is not automatically a pulsed heartbeat. Match the RTU's expected contact behaviour. Loss of the RTU watchdog input invokes the configured contractual-power fallback. Confirm the input polarity and recovery sequence during commissioning.
See also wiring and connectivity guidelines, relay-Ethernet converters and the dS1242 module guide.