ADA PN100 – Pulse from P1 to PLC (RJ12 Pulse P1)

Want the good old S0/pulse output back from your smart meter? The ADA PN100 does exactly that: it reads energy data from the meter’s P1 (DSMR) port and generates programmable pulses to feed your PLC/SCADA counter input – just like connecting a classic kWh meter’s S0 output.

What is it for?

A bridge between old and new worlds: modern smart meters output text data via the P1 port, while many industrial systems still expect pulses. The PN100 converts this P1 data into pulses (e.g., 100 Wh/pulse).
Easy upgrade: no need to rewrite existing PLC code – the PN100 emulates the old “clicking” counter, just silently and precisely.
Counts where it matters: metering, billing, consumer profiling, sub-metering – all can remain in the same industrial logic.

How does it work?

The PN100 reads the P1 port (DSMR) value such as 1-0:1.8.0 (total import kWh) or any selected OBIS code.
It accumulates the measured increment, and when the set threshold is reached (e.g., 100 Wh), it outputs a pulse (with programmable duration, e.g., 300 ms).
The output emulates a voltage-free contact, suitable for 24 V PLC digital inputs (galvanically isolated with PhotoMOS/optocoupler).
No double counting after power loss: PN100 stores the last kWh value and remaining fraction, resuming accurately after reboot.

Main features

Fully configurable via web browser
– OBIS code (default: 1-0:1.8.0)
– Pulse length (typically 200–500 ms, default: 300 ms)
– Energy per pulse (default: 100 Wh)
Web interface (AP mode, captive portal): the device starts its own Wi-Fi network ADA-PN100, password: 12345678.
Test pulse button: perfect for on-site commissioning.
Blue status LED: flashes during pulse, triple blink on startup.
Logging: built-in 500-line ring log stored in LittleFS (retained after power loss), accessible at /log endpoint with auto-refresh.
Timestamp in log: taken from the P1 0-0:1.0.0 field (if available).
Reliable counting: last kWh and remainder stored in EEPROM – no lost or duplicated pulses.

Wiring – typical PLC/SCADA 24 V DI

S0+ → PLC/SCADA +24 V
S0− → PLC DI, through PhotoMOS/optocoupler (galvanic isolation) → isolated GND
On the PN100 side, a small driver activates a PhotoMOS relay, so the PLC sees a voltage-free contact.
Recommended components (examples): TLP175A, AQY212, AQY282 (low leakage, ideal for 24 V DC).

Note: a simple FET/open collector does not provide galvanic isolation. In industrial environments, PhotoMOS/optocoupler coupling is strongly recommended.

Web interface

AP mode: configure directly from your phone on site.
Pages:
– Main: settings (OBIS, pulse width, Wh/pulse), buttons (Save / Test / Delete log), log viewer (newest first).
– /log: raw log list, auto-refresh every second (with built-in JS).
UX details: mobile-first layout, separate buttons for test pulse and log deletion.

Smart functions

Fine step detection: many meters increment by 1/128 kWh (~7.8125 Wh); the PN100 accumulates these precisely and fires a pulse once the threshold (e.g. 100 Wh) is reached.
Rollback handling: if the meter value decreases (e.g., after tariff reset or power failure), a new base point is set.
Service-friendly log: lines with [OBIS], [PULSE], [BASE], [RESET] and DSMR timestamps – for quick diagnostics.

Technical summary

Input: P1 (DSMR v4/v5), 115200 8N1 (inverted), OBIS-based reading
Output: voltage-free contact emulation via PhotoMOS/optocoupler (recommended) to PLC 24 V DC DI
Pulse width: 50–2000 ms (recommended 200–500 ms), default 300 ms
Scale: 1–100 000 Wh/pulse (default 100 Wh)
Indication: blue LED flashes during pulse; 3× flash on boot
Local service: Wi-Fi AP (SSID: ADA-PN100), built-in web UI, captive portal
Persistence: EEPROM (last kWh + remainder), LittleFS (log ~40 kB)
Up-to-date: log auto-refresh, /log endpoint

Compatibility and tips

Supported meters: DSMR-compatible P1 smart meters (typically reading OBIS 1-0:1.8.0; can be changed if needed).
Compatible PLCs: any controller that accepts 24 V counter/digital input and pulse width around 200–500 ms (industrial standard filtering range).
Commissioning tip: temporarily set scale to 8 or 16 Wh/pulse for fast verification of pulse rhythm in the log.

FAQ

Is this really an open-collector-style, voltage-free contact?
Yes, using PhotoMOS/optocoupler isolation, the PN100 switches the PLC’s 24 V loop galvanically separated.

What happens during power loss?
The last kWh and stored “remainder” are saved to EEPROM, so the PN100 does not double-count or lose data.

Does it only support 1-0:1.8.0?
That’s the default, but the OBIS code is editable via the web UI – any register can be monitored intentionally.

Recommended pulse duration?
Typically 200–500 ms in industrial setups; factory default is 300 ms.

Summary

The ADA PN100 brings back the convenience of the classic S0 pulse into the smart-meter world. Compact, silent, web-configurable, and PLC-ready. If you want to keep your existing counter logic but with modern meters, the PN100 is the simplest and most robust solution.