AEM-60DC8 Modbus RTU/TCP Slave Simulator

May 31, 2026 · View on GitHub

Open-source Python simulator that emulates the full holding-register map of the LRI AEM-60DC8 industrial DC voltage monitor.

Lets SCADA / HMI / PLC integrators develop and test their Modbus integration without the physical hardware on the bench — useful for offline development, CI pipelines, and training environments.

What it simulates

8 independent DC voltage channels (0-60V, ±1% accuracy emulation)
NTC temperature sensor with realistic drift
147 holding registers in 17 functional blocks (full map at https://aem.lri.com.br/en-us/modbus)
Six baudrates: 4800 / 9600 / 19200 / 38400 / 57600 / 115200
Function codes 03 (Read Holding) and 16 (Write Multiple)
Exception 02 on invalid address
Configurable presets for telecom 48V, solar strings, automotive 24V scenarios

Quick start

Install

pip install pymodbus pyserial

Run as Modbus TCP server (no hardware needed)

python aem_60dc8_slave.py --tcp 0.0.0.0:5020 --slave-id 1

Run as Modbus RTU over USB-RS485

# Linux / macOS
python aem_60dc8_slave.py --port /dev/ttyUSB0 --baud 19200 --slave-id 1

# Windows
python aem_60dc8_slave.py --port COM3 --baud 19200 --slave-id 1

Test from any Modbus client

from pymodbus.client import ModbusTcpClient

c = ModbusTcpClient("127.0.0.1", port=5020)
c.connect()

# Read 8 DC channels (V, scaled ×100)
r = c.read_holding_registers(0, count=8, slave=1)
voltages = [v / 100.0 for v in r.registers]
print(f"Channels (V): {voltages}")

# Read NTC temperature (°C, scaled ×100)
t = c.read_holding_registers(8, count=1, slave=1)
print(f"Temperature (°C): {t.registers[0] / 100.0}")

Register map (excerpt)

Address	Name	Type	Scale	Unit	R/W
40001-40008	Voltage CH1..CH8	uint16	×100	V	R
40009	NTC Temperature	int16	×100	°C	R
40010-40011	NTC min / max threshold	int16	×100	°C	R/W
40012-40027	Per-channel min/max thresh	uint16	×100	V	R/W
40028	Baudrate index (0-5)	uint16	—	—	R/W
40029	Slave address	uint16	—	—	R

Full 147-register map with all 17 functional blocks (alarms, telemetry, anti-rollback counters, RTOS health, etc) is documented and interactively browsable at:

https://aem.lri.com.br/en-us/modbus

Use cases

SCADA integration testing (Ignition, Elipse E3, AVEVA InTouch, WinCC, etc.)
PLC program development without physical hardware
CI/CD pipelines for industrial automation projects
Engineering training and educational labs
Pre-deployment validation before site commissioning

Customization

Edit the CHANNELS list in aem_60dc8_slave.py (or use the presets in examples/) to model your deployment scenario:

CHANNELS: list[Channel] = [
    Channel("BAT CELL A", 53.6, 0.18, 48.0, 57.6),
    Channel("BAT CELL B", 53.7, 0.18, 48.0, 57.6),
    # ... 6 more channels
]

See examples/ for ready-to-use presets:

telecom_48v_bank.py — 8-cell 48V telecom battery bank
solar_strings.py — 8 PV strings monitoring
automotive_24v.py — 24V automotive auxiliary systems

About the real hardware

The simulator emulates the LRI AEM-60DC8, an industrial DC voltage monitoring platform with:

8 independent DC channels (0-60V, 30V and 150V variants)
5000 VAC rms galvanic isolation on opto-isolated digital inputs
Modbus RTU over RS-485 (4,800-115,200 bps)
Ed25519-signed firmware with 9-layer boot validation
IEC 62443-4-2 Security Level 2 target
16×4 LCD with 3-key navigation
35 mm DIN rail mounting, UL94 V-0 flame retardant
Manufactured in Brazil by LRI Automação Industrial

For technical documentation, datasheet, and the interactive Modbus map: https://aem.lri.com.br/en-us

Contributing

Pull requests welcome! Common contributions:

Additional preset scenarios in examples/
Better simulation realism (drift patterns, noise models, fault injection)
Additional Modbus function codes (currently 03 and 16)
TCP/RTU bridging examples
Test fixtures

See CONTRIBUTING.md for guidelines.

This simulator is provided as-is by LRI Automação Industrial for the engineering community. The real AEM-60DC8 firmware and hardware are proprietary; only the Modbus map (which is a public interface anyway) is mirrored here.