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P1 Modbus Pro (NRGD)

Hardware, connections, power and installation for P1 Modbus Pro (NRGD).

P1 Modbus Pro is the compact Smartstuff smart-meter-to-Modbus RTU adapter. NRGD is its product family and may appear in the Device Manager or support information. Two hardware implementations exist within this family.

P1 Modbus Pro with removable Modbus RTU terminal connector
P1 Modbus Pro (NRGD).

NRGD implementations

The regular NRGD and the newer implementation based on ZAP2/NRGDH use the same enclosure and cannot be distinguished reliably by the enclosure alone. Check the connection sticker and LEDs on the dongle:

Characteristic
Regular NRGD
ZAP2/NRGDH-based NRGD

Hardware basis

NRGD

ZAP2/NRGDH

Smart-meter input

DSMR/P1

DSMR/P1 or HAN-NVE; HAN-NVE requires a HAN (RJ45)-to-RJ12 cable

Modbus A and B

Use the connection sticker on the dongle

Different A/B terminal positions; use the connection sticker on the dongle

Status LED

Separate blue mono status LED

No separate blue status LED; RGB status LED in the P1 input, in the position used by the green LED on the regular NRGD. Its colors have the same meaning as on D1MC

The A and B positions differ between the two implementations. Never copy the terminal order from another NRGD dongle or from an image: always follow the connection sticker on the dongle being installed.

Features and connections

  • DSMR/P1 input through the supplied P1 cable

  • HAN-NVE input on the ZAP2/NRGDH-based implementation, using a HAN (RJ45)-to-RJ12 cable

  • Modbus RTU through the removable RS485 module terminal connector

  • USB-C for additional 5 V power, local configuration and firmware updates

  • P1 output

  • P1 output LED; the power and status indication differs by implementation as shown above

  • Button for reboot, factory reset and download mode

P1 Modbus Pro does not support Linky TIC and does not have software-controlled RS485 termination.

Modbus RTU terminal

Regular NRGD
ZAP2/NRGDH-based NRGD

Regular P1 Modbus Pro NRGD terminal order: GND, A positive, B negative

ZAP2/NRGDH-based P1 Modbus Pro terminal order: B negative, GND, A positive

From top to bottom: GND, A+, B-

From top to bottom: B-, GND, A+

Match the A, B and, when required, GND labels to the connected Modbus device. In most installations only A and B are required. Follow the connected device manufacturer's instructions and use a suitable twisted pair.

Do not use the pin-out of the old white P1 Modbus adapter or another NRGD implementation. Their terminal order may be different.

Power

The adapter is normally powered from a suitable DSMR/P1 meter. Connect an external regulated 5 V USB power supply through USB-C when the meter cannot provide sufficient power. USB-C is also used with a USB data cable for the Device Manager and firmware updates.

The P1 output is powered only while USB power is connected.

Installation

  1. Disconnect power from the equipment involved before wiring Modbus RTU.

  2. Connect the P1 Modbus Pro to the meter with the supplied P1 cable.

  3. Add a 5 V USB-C supply if the meter cannot supply sufficient power or if the P1 output must be powered.

  4. Identify the NRGD implementation from its connection sticker and LEDs, then connect Modbus RTU using the A and B labels on that dongle.

  5. Apply power and connect through the Device Manager.

  6. Configure the Modbus communication settings to match the connected controller.

LEDs and button

The RGB status LED on the ZAP2/NRGDH-based implementation uses the same colors and indications as D1MC. See LED indicators for firmware v2 status behavior.

  • Short press: reboot.

  • Press for more than 5 seconds: restore factory settings and reboot.

  • Hold while applying power: enter download mode.

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