Setup Environment for SCADA Edge Processing

Before building the pipeline, let's set up a Modbus TCP environment and generate realistic substation telemetry for testing.

Prerequisites

Expanso Edge Installation

If you haven't installed Expanso Edge yet:

# Download and install Expanso Edge
curl -sSL https://get.expanso.io | sh
sudo systemctl enable --now expanso-edge

Verify installation:

expanso version
# Expected: Expanso Edge v2.x.x

Access Requirements

You'll need one of the following:

Physical RTU/PLC with Modbus TCP enabled on your OT network (port 502)
Modbus TCP simulator (recommended for development/testing)
Network access through your substation DMZ or a controlled test network

OT Network Safety

Never connect development tooling directly to live substation equipment without OT team approval and a proper change management process. Use a simulator or isolated test network for development.

Step 1: Install Modbus TCP Simulator

For testing without physical RTU hardware, install a Modbus TCP slave simulator:

Option A: diagslave (Linux/macOS)

# Download diagslave from FieldTalk (free for non-commercial use)
# https://www.modbusdriver.com/diagslave.html
wget https://www.modbusdriver.com/downloads/diagslave.zip
unzip diagslave.zip
sudo cp diagslave/linux_x86-64/diagslave /usr/local/bin/

# Start as Modbus TCP slave on port 502 with device ID 1
sudo diagslave -m tcp -p 502 1

Option B: modbus-simulator (Python-based, cross-platform)

# Install via pip
pip install pymodbus

# Create a simple simulator script
cat > modbus_simulator.py << 'EOF'
from pymodbus.server.sync import StartTcpServer
from pymodbus.datastore import ModbusSlaveContext, ModbusServerContext
from pymodbus.datastore import ModbusSequentialDataBlock
import threading
import time
import random

def create_context():
    # Holding registers (40001 onwards)
    # REG 40001: Voltage (V x100) — normal: 11500-14500 (115-145 kV)
    # REG 40003: Current (A x10)  — normal: 0-5000 (0-500 A)
    # REG 40005: Frequency (Hz x100) — normal: 5995-6005 (59.95-60.05 Hz)
    # REG 40007: Temperature (degC x10) — normal: 0-750 (0-75°C)
    # REG 40009: Power (MW x10) — normal: 0-5000 (0-500 MW)
    registers = [
        0,      # pad (address 0)
        14823,  # REG 40001: voltage 148.23 kV
        0,      # pad
        2341,   # REG 40003: current 234.1 A
        0,      # pad
        6001,   # REG 40005: frequency 60.01 Hz
        0,      # pad
        423,    # REG 40007: temp 42.3°C
        0,      # pad
        2847,   # REG 40009: power 284.7 MW
    ]
    store = ModbusSlaveContext(
        hr=ModbusSequentialDataBlock(0, registers)
    )
    return ModbusServerContext(slaves=store, single=True)

context = create_context()
print("Starting Modbus TCP simulator on 0.0.0.0:502")
StartTcpServer(context, address=("0.0.0.0", 502))
EOF

sudo python3 modbus_simulator.py

Option C: Docker-based simulator

docker run -d \
  --name modbus-sim \
  -p 502:502 \
  --env MODBUS_SLAVE_ID=1 \
  oitc/modbus-server:latest

Step 2: Configure Environment Variables

Set these environment variables before deploying the pipeline:

# Substation identity
export SUBSTATION_ID="SUB-CENTRAL-01"
export GRID_REGION="WECC-SOUTHWEST"
export RTU_DEVICE_PREFIX="RTU-07"

# SCADA historian (your existing SCADA system's API endpoint)
export SCADA_HISTORIAN_URL="https://historian.internal.example.com/api/v1/events"
export HISTORIAN_API_KEY="your-historian-api-key"

# PagerDuty for critical fault alerting
export PAGERDUTY_WEBHOOK_URL="https://events.pagerduty.com/v2/enqueue"
export PAGERDUTY_ROUTING_KEY="your-pagerduty-routing-key"

# Grafana Cloud for KPI dashboards (CIP-safe aggregated data only)
export GRAFANA_CLOUD_URL="https://influx.grafana.net/api/v1/push/influx/write"
export GRAFANA_API_KEY="your-grafana-api-key"

# Local audit archive (NERC CIP §R1.4 — full raw data stays local)
export LOCAL_AUDIT_PATH="/var/lib/expanso/scada-audit"

# Fault classification thresholds (NERC reliability standards)
export VOLTAGE_MIN_KV="110.0"
export VOLTAGE_MAX_KV="145.0"
export FREQ_MIN_HZ="59.95"
export FREQ_MAX_HZ="60.05"
export TEMP_MAX_C="75.0"

Apply to your shell:

# Add to ~/.bashrc or /etc/environment for persistence
source ~/.bashrc

# Or create an env file for the pipeline
cat > /etc/expanso/scada-edge.env << 'ENVEOF'
SUBSTATION_ID=SUB-CENTRAL-01
GRID_REGION=WECC-SOUTHWEST
SCADA_HISTORIAN_URL=https://historian.internal.example.com/api/v1/events
PAGERDUTY_WEBHOOK_URL=https://events.pagerduty.com/v2/enqueue
GRAFANA_CLOUD_URL=https://influx.grafana.net/api/v1/push/influx/write
LOCAL_AUDIT_PATH=/var/lib/expanso/scada-audit
ENVEOF

Step 3: Generate Sample Modbus Data for Testing

Use this script to generate realistic RTU telemetry — including occasional fault conditions:

cat > /var/lib/expanso/generate-modbus-data.sh << 'EOF'
#!/bin/bash
# Generate sample Modbus register data for Expanso pipeline testing
# Outputs semicolon-delimited key=value lines simulating RTU polling

DEVICE="RTU-07A"
TS=$(date +%s)

# Normal readings (90% of the time)
generate_normal() {
  local ts=$1
  echo "REG=40001;VAL=14823;UNIT=V_x100;TS=${ts};DEVICE=${DEVICE};STATUS=0"
  echo "REG=40003;VAL=2341;UNIT=A_x10;TS=${ts};DEVICE=${DEVICE};STATUS=0"
  echo "REG=40005;VAL=6001;UNIT=Hz_x100;TS=${ts};DEVICE=${DEVICE};STATUS=0"
  echo "REG=40007;VAL=423;UNIT=degC_x10;TS=${ts};DEVICE=${DEVICE};STATUS=0"
  echo "REG=40009;VAL=2847;UNIT=MW_x10;TS=${ts};DEVICE=${DEVICE};STATUS=0"
}

# Voltage deviation (undervoltage event — 104.5 kV, below 110 kV threshold)
generate_voltage_fault() {
  local ts=$1
  echo "REG=40001;VAL=10450;UNIT=V_x100;TS=${ts};DEVICE=${DEVICE};STATUS=2"
  echo "REG=40003;VAL=4820;UNIT=A_x10;TS=${ts};DEVICE=${DEVICE};STATUS=2"
  echo "REG=40005;VAL=5992;UNIT=Hz_x100;TS=${ts};DEVICE=${DEVICE};STATUS=0"
  echo "REG=40007;VAL=512;UNIT=degC_x10;TS=${ts};DEVICE=${DEVICE};STATUS=0"
  echo "REG=40009;VAL=2710;UNIT=MW_x10;TS=${ts};DEVICE=${DEVICE};STATUS=0"
}

# Thermal overload (87.3°C — above 75°C threshold)
generate_thermal_fault() {
  local ts=$1
  echo "REG=40001;VAL=14100;UNIT=V_x100;TS=${ts};DEVICE=${DEVICE};STATUS=0"
  echo "REG=40003;VAL=4901;UNIT=A_x10;TS=${ts};DEVICE=${DEVICE};STATUS=1"
  echo "REG=40005;VAL=5999;UNIT=Hz_x100;TS=${ts};DEVICE=${DEVICE};STATUS=0"
  echo "REG=40007;VAL=873;UNIT=degC_x10;TS=${ts};DEVICE=${DEVICE};STATUS=1"
  echo "REG=40009;VAL=4890;UNIT=MW_x10;TS=${ts};DEVICE=${DEVICE};STATUS=0"
}

# Generate a stream of readings
for i in $(seq 1 100); do
  ts=$(date +%s)
  rand=$((RANDOM % 10))

  if [ "$rand" -eq 0 ]; then
    generate_voltage_fault $ts
  elif [ "$rand" -eq 1 ]; then
    generate_thermal_fault $ts
  else
    generate_normal $ts
  fi

  sleep 0.5
done
EOF

chmod +x /var/lib/expanso/generate-modbus-data.sh

Run the generator:

/var/lib/expanso/generate-modbus-data.sh

Example output:

REG=40001;VAL=14823;UNIT=V_x100;TS=1708290845;DEVICE=RTU-07A;STATUS=0
REG=40003;VAL=2341;UNIT=A_x10;TS=1708290845;DEVICE=RTU-07A;STATUS=0
REG=40005;VAL=6001;UNIT=Hz_x100;TS=1708290845;DEVICE=RTU-07A;STATUS=0
REG=40007;VAL=423;UNIT=degC_x10;TS=1708290845;DEVICE=RTU-07A;STATUS=0
REG=40009;VAL=2847;UNIT=MW_x10;TS=1708290845;DEVICE=RTU-07A;STATUS=0
REG=40001;VAL=10450;UNIT=V_x100;TS=1708290846;DEVICE=RTU-07A;STATUS=2  ← voltage fault

Step 4: Verify Connectivity

Before deploying the pipeline, verify each component:

Check Modbus TCP Simulator

# Test Modbus TCP connection (requires modbus-cli or similar)
nc -zv localhost 502
# Expected: Connection to localhost (127.0.0.1) 502 port [tcp/modbus] succeeded!

Check Historian Endpoint

curl -sf -o /dev/null -w "%{http_code}" \
  -H "Authorization: Bearer $HISTORIAN_API_KEY" \
  "$SCADA_HISTORIAN_URL/health"
# Expected: 200

Check PagerDuty Webhook

curl -X POST "$PAGERDUTY_WEBHOOK_URL" \
  -H "Content-Type: application/json" \
  -d '{
    "routing_key": "'"$PAGERDUTY_ROUTING_KEY"'",
    "event_action": "trigger",
    "payload": {
      "summary": "Expanso pipeline connectivity test",
      "severity": "info",
      "source": "expanso-setup"
    }
  }'
# Expected: {"status":"success","message":"Event processed"}

Create Local Audit Directory

sudo mkdir -p $LOCAL_AUDIT_PATH
sudo chown expanso:expanso $LOCAL_AUDIT_PATH
sudo chmod 750 $LOCAL_AUDIT_PATH

# Verify write access
touch $LOCAL_AUDIT_PATH/.write-test && rm $LOCAL_AUDIT_PATH/.write-test
echo "✓ Audit directory ready: $LOCAL_AUDIT_PATH"

What's Next?

Your environment is ready. Now build the first pipeline stage — parsing raw Modbus register values into structured engineering units.

→ Next Step: Step 1: Parse Modbus Register Data

Pro Tip: Run the data generator in the background for continuous testing:

nohup /var/lib/expanso/generate-modbus-data.sh > /tmp/modbus-test-data.log 2>&1 &
echo "Generator PID: $!"

Prerequisites​

Expanso Edge Installation​

Access Requirements​

Step 1: Install Modbus TCP Simulator​

Option A: diagslave (Linux/macOS)​

Option B: modbus-simulator (Python-based, cross-platform)​

Option C: Docker-based simulator​

Step 2: Configure Environment Variables​

Step 3: Generate Sample Modbus Data for Testing​

Step 4: Verify Connectivity​

Check Modbus TCP Simulator​

Check Historian Endpoint​

Check PagerDuty Webhook​

Create Local Audit Directory​

What's Next?​