ADA-PN100 – P1 → S0 Pulse Generator

The ADA-PN100 is an ESP32-based device that generates S0 (countable) pulses from OBIS data read from the P1 port of smart meters. Its purpose is to provide compatible pulse signals from modern smart meter energy values to PLCs, measurement systems, data collectors, or SCADA systems.

In brief: P1 OBIS → processing → configurable duration (ms) and quantity (Wh/pulse) S0-like pulses on an isolated, potential-free PhotoMOS output (GAQY212GS).

What is it for?

Driving old S0 counters/PLC inputs from smart meter data.
Consumption/production pulse output (kWh-based), compatible with industrial 24 VDC digital inputs.
Separated PV export/import pulses with distinct OBIS codes (e.g. imported: 1-0:1.8.0, fed-in: 2-0:2.8.0).
Easy integration with data collectors, loggers, BMS/EMS/SCADA systems that expect pulses.

Main features

OBIS-based processing: 1-0:1.8.0 (default, kWh), other OBIS codes can be specified.
Configurable pulse length: 50–2000 ms (default: 300 ms).
Configurable Wh/pulse (e.g. 100 Wh → 0.1 kWh/pulse).
Stability: EEPROM-stored state (baseline + residual kWh), no doubling after power failure.
Built-in logging: memory buffer + LittleFS file (/pn100.log), viewable in browser.
Physical factory reset button (GPIO4): press for ≥5 s → factory reset.
Isolated output: PhotoMOS SSR (GAQY212GS), potential-free, SPST-NO, up to 60 VAC/DC, 500 mA.

Hardware – Output relay (GAQY212GS)

Relay type	Solid-state semiconductor relay (PhotoMOS), SPST-NO
Manufacturer code	GAQY212GS (SUPSIC), OptoMOS series
Package	SOP-4 (SMT)
Isolation	1.5 kV (optical isolation on output)
Switching time	on: ~0.35 ms, off: ~0.1 ms
On-state resistance	~0.8 Ω (when on)
Max. output current	500 mA
Max. voltage	60 VAC / 60 VDC
Control current (LED side)	max. 50 mA (typically 5–10 mA suffices)
Operating temperature	−40…+85 °C

Note: A small leakage current is natural in PhotoMOS relays (in the µA range). Standard PLC digital inputs are typically not disturbed by this.

Warning: the output can be used only in circuits up to 60 V AC/DC. Never connect directly to 230 VAC mains!

Switching logic (S0 / "dry contact")

The PhotoMOS output is normally open (NO). On pulse, it closes → the 24 V PLC input circuit short-circuits briefly.
The two terminals are polarity-independent (suitable for AC/DC up to 60 V limit).
Typical wiring: PLC +24V → input → PN100 PhotoMOS → 0V in series, or directly to PLC input S0+ / S0− terminals.

Simple wiring example (for 24 VDC PLC input)

+24V  ──► PLC DI+ ──► [ GAQY212GS (PN100) ] ──► 0V (GND)

Web setup (AP mode)

After powering on, the device starts in AP mode: SSID: ADA-PN100, password: 12345678 (changeable).
Connect to the AP, then open in browser: http://192.168.4.1.
Main fields on the interface:
- OBIS code – the read OBIS identifier (default: 1-0:1.8.0).
- Pulse length (ms) – pulse duration (50–2000 ms; default: 300 ms).
- Quantity (Wh/pulse) – Wh per pulse (e.g. 100 Wh → 0.1 kWh).
- AP password – access password (8–63 characters). After saving, the AP restarts automatically.
Save – save settings to EEPROM.
Test pulse – test pulse (quick check of hardware and PLC input).
Delete log – clear log.
Log – newest entries on top, auto-updates every 5 s. Separate endpoint: /log?format=html|text&rev=1|0

Factory reset (physical button)

Button on GPIO4, INPUT_PULLUP mode.
Hold for ≥5 s → device resets all settings (OBIS, pulse parameters, AP password, log) and restarts to factory defaults.

OBIS ideas (not just the default)

OBIS	Meaning	Typical use
`1-0:1.8.0`	Total imported energy (kWh)	Counting consumption (default)
`2-0:2.8.0`	Total fed-in energy (kWh)	Separate counter for PV export pulses
`1-0:1.7.0`	Instantaneous import power (kW)	“Power-proportional” pulse (requires kW→Wh integration)
`2-0:2.7.0`	Instantaneous export power (kW)	Export-dependent pulse densification (e.g. PV regulation)
`1-0:21.7.0/41.7.0/61.7.0`	Instantaneous import (kW) on L1/L2/L3	Phase-wise pulses (using three separate PN100 units)
`1-0:32.7.0`	Phase voltage L1 (V)	Counting voltage threshold events (for custom logic)

The ADA-PN100 firmware primarily outputs kWh-based pulses but can read arbitrary OBIS codes. If you specify a non-kWh type code (e.g. kW), then to correct the quantity (Wh/pulse), it is advisable to extend the firmware with integral logic (project-dependent).

Selecting pulse density

The Wh/pulse value determines how frequently pulses occur. Example:

Load: 3 kW (≈ 3000 W) → 3000 Wh of energy per hour.
If 100 Wh/pulse, then 3000/100 = 30 pulses/hour → on average, one every 2 minutes.
If 10 Wh/pulse, then 3000/10 = 300 pulses/hour → on average, one every 12 seconds.

General PLCs can definitely count pulse lengths of 30–300 ms. The firmware allows a range of 50–2000 ms.

Compatibility (examples, not exhaustive)

PLCs with 24 VDC digital inputs or dedicated S0 counter inputs: Siemens LOGO!/S7 DI, WAGO, Omron, Schneider, FATEK, Unitronics, etc.
Data collectors / energy monitors expecting potential-free contact inputs.
Impulse counters connecting to SCADA systems.

Key: the PN100 output emulates a dry contact (PhotoMOS), making it widely compatible with the 24 VDC industrial environment.

System architecture (overview)

Smart meter (P1, inverted DSMR 115200)  ──►  ADA-PN100 (ESP32)
                                           ├─ OBIS processing, EEPROM persistence
                                           ├─ Web UI (AP): \/, \/save, \/test, \/clear_log, \/log
                                           └─ PhotoMOS SSR pulses  ──► PLC/Logger/SCADA (24 VDC input)

Software features (web and API endpoints)

Endpoint	Description
`/`	Settings interface (OBIS, pulse ms, Wh/pulse, AP password) + live log
`/save` (POST)	Save settings to EEPROM (AP password 8–63 characters)
`/test`	Send single test pulse
`/clear_log`	Clear log file and RAM buffer
`/log?format=html\|text&rev=1\|0`	Show log (also in reverse order)

Installation and commissioning

Hardware wiring: Connect PN100 PhotoMOS output in series with the 24 V PLC input circuit. Pay attention to the max. 60 V and 500 mA limits.
Power supply: USB or 5 V VIN to ESP32 module (typically < 200 mA).
Web setup: Connect to AP → http://192.168.4.1 → fill fields → Save.
Change AP password (optional): after saving, AP restarts, connect with new password.
Testing: press Test pulse button → check PLC counter increments.

Troubleshooting

No pulses: Does Test pulse work? If yes, the issue may be with P1/OBIS processing (kWh not increasing). Check OBIS code and assure it actually changes.
PLC does not count: Is input type correct? 24 VDC DI or S0 counter is required. Minimum pulse length should be above 30–50 ms.
Occasional false pulses: At very high impedance inputs, PhotoMOS leakage may cause sensitivity. Add a weak pull-down resistor (e.g. 10–47 kΩ) between input and 0V.
Cannot connect to AP: hold RESET button ≥5 s and restart with factory password.

Safety and limits

Max. 60 VAC/DC output voltage! Do not connect to 230 VAC mains.
The pulse output is isolated PhotoMOS, potential-free, but in industrial environments pay attention to wiring (shielded or short cable, common reference with PLC if needed).
The firmware uses inverted DSMR 115200 8N1 setting for the P1 port.

Technical summary

MCU	ESP32 (UART2: RX=16, TX=17, inverted)
Output	GAQY212GS PhotoMOS, SPST-NO, 60 VAC/DC, 500 mA, ~0.8 Ω
Pulse length	50–2000 ms (default: 300 ms)
Scale	Wh/pulse (user adjustable; default: 100 Wh)
OBIS	Default: `1-0:1.8.0`; others configurable
Log	RAM buffer 500 lines + LittleFS (`/pn100.log`), /log endpoint
AP mode	SSID: ADA-PN100; password editable (8–63 chars)
Factory reset	GPIO4 button ≥5 s → factory default
Power	5 V (USB/VIN), typically < 200 mA

Hardware drive tips

For the SSR LED from 3.3 V, typically 180–470 Ω series resistor is enough (for 8 mA, ~270 Ω can be calculated as starting point).
On the PLC side, input filtering (debounce/pulse timing) should be set above 20–30 ms.

Commissioning

© GreenHESS / ADA-PN100 – technical documentation. The compatibility list is not exhaustive, the input specifications of individual PLCs may vary. The output is suitable only for max 60 VAC/DC circuits.