Protocols & Connections

TwinEdge Edge supports a wide range of industrial communication protocols to connect with your equipment.

Supported Protocols

Protocol	Type	Common Use Cases
OPC UA	Client/Server	PLCs, SCADA, modern equipment
Modbus TCP	Client	PLCs, sensors, actuators
Modbus RTU	Serial	Legacy sensors, meters
MQTT	Pub/Sub	IoT sensors, custom devices
EtherNet/IP	Client	Allen-Bradley, Rockwell
S7	Client	Siemens PLCs
BACnet	Client	Building automation

OPC UA

Overview

OPC UA (Unified Architecture) is the modern standard for industrial interoperability, providing secure, reliable data exchange.

Connecting to OPC UA Server

1. Go to Data Sources → Add Data Source
2. Select OPC UA
3. Enter connection details:
   • Name: Descriptive name
   • Endpoint URL: opc.tcp://192.168.1.100:4840
   • Security Mode: None, Sign, SignAndEncrypt
   • Security Policy: Basic256Sha256 (recommended)

Authentication

Anonymous:

endpoint: opc.tcp://server:4840
security_mode: None

Username/Password:

endpoint: opc.tcp://server:4840
security_mode: SignAndEncrypt
security_policy: Basic256Sha256
username: operator
password: ********

Certificate:

endpoint: opc.tcp://server:4840
security_mode: SignAndEncrypt
security_policy: Basic256Sha256
certificate_path: /certs/client.pem
private_key_path: /certs/client.key

Browsing Tags

After connecting:

1. Click Browse Tags
2. Navigate the namespace tree
3. Expand Objects → Your Device → Variables
4. Check tags to monitor
5. Click Add Selected

Tag Configuration

For each tag, configure:

• Polling Interval: How often to read (100ms - 1h)
• Deadband: Minimum change to report (absolute or %)
• Alias: Friendly name for dashboards

Subscriptions

For real-time data, use OPC UA subscriptions:

subscription:
  publishing_interval_ms: 1000
  lifetime_count: 10000
  max_keep_alive_count: 10
  max_notifications_per_publish: 1000

Modbus TCP

Overview

Modbus TCP is widely supported by industrial equipment for register-based communication.

Connection Setup

1. Go to Data Sources → Add Data Source
2. Select Modbus TCP
3. Enter details:
   • Name: Device name
   • Host: 192.168.1.50
   • Port: 502 (default)
   • Unit ID: 1 (slave address)

Register Types

Type	Function Code	Address Range	Data Type
Coils	01, 05, 15	00001-09999	Boolean
Discrete Inputs	02	10001-19999	Boolean
Input Registers	04	30001-39999	16-bit
Holding Registers	03, 06, 16	40001-49999	16-bit

Configuring Registers

Add registers to monitor:

registers:
  - name: temperature
    address: 40001
    type: holding
    data_type: float32
    byte_order: big_endian
    scale: 0.1
    unit: "°C"

  - name: pressure
    address: 40003
    type: holding
    data_type: uint16
    scale: 0.01
    unit: "bar"

Data Types

Type	Registers	Example
int16	1	-32768 to 32767
uint16	1	0 to 65535
int32	2	Signed 32-bit
uint32	2	Unsigned 32-bit
float32	2	IEEE 754 float
float64	4	IEEE 754 double
string	N	ASCII string

Byte Order

Configure based on device manufacturer:

• big_endian: Most significant byte first (AB CD)
• little_endian: Least significant byte first (CD AB)
• big_endian_swap: Word swap (CD AB)
• little_endian_swap: Word swap (AB CD)

Modbus RTU (Serial)

Hardware Setup

Connect via RS-485 adapter:

1. USB to RS-485 converter
2. Connect A+/B- terminals
3. Configure termination if needed

Connection Settings

serial:
  port: /dev/ttyUSB0
  baudrate: 9600
  parity: none
  stopbits: 1
  bytesize: 8
  timeout_seconds: 1

Multi-Drop Setup

Connect multiple devices on same bus:

devices:
  - name: meter_1
    unit_id: 1
    registers: [...]

  - name: meter_2
    unit_id: 2
    registers: [...]

MQTT

Connecting to MQTT Broker

1. Go to Data Sources → Add Data Source
2. Select MQTT
3. Enter broker details:
   • Host: mqtt.company.com
   • Port: 1883 (or 8883 for TLS)
   • Username: Optional
   • Password: Optional

Topic Subscriptions

Subscribe to topics:

subscriptions:
  - topic: factory/line1/+/temperature
    qos: 1

  - topic: sensors/#
    qos: 0

Payload Parsing

JSON:

{"temperature": 25.5, "humidity": 60.2, "timestamp": "2026-01-06T10:00:00Z"}

payload_format: json
mappings:
  - json_path: $.temperature
    tag_name: temperature
  - json_path: $.humidity
    tag_name: humidity

Raw Value:

payload_format: raw
data_type: float

EtherNet/IP

Connection Setup

For Allen-Bradley and Rockwell controllers:

host: 192.168.1.100
slot: 0
timeout_ms: 5000

Tag Reading

tags:
  - name: LocalTags:Temperature
    alias: temp
    poll_ms: 1000

  - name: Program:MainProgram.Speed
    alias: motor_speed
    poll_ms: 500

S7 Protocol

Connection Setup

For Siemens S7-300/400/1200/1500:

host: 192.168.1.100
rack: 0
slot: 1
port: 102

Data Block Reading

data_blocks:
  - db_number: 1
    items:
      - name: temperature
        offset: 0
        type: real

      - name: status
        offset: 4
        type: int

Connection Health

Monitoring Connections

View connection status:

• Connected: Active communication
• Reconnecting: Attempting to restore
• Disconnected: No communication
• Error: Configuration or network issue

Automatic Reconnection

TwinEdge automatically handles:

• Network interruptions
• Device restarts
• Temporary failures

reconnection:
  enabled: true
  initial_delay_ms: 1000
  max_delay_ms: 60000
  backoff_multiplier: 2

Connection Alerts

Configure alerts for connection issues:

alerts:
  - condition: disconnected > 5 minutes
    severity: critical
    notification: email, slack

Troubleshooting

OPC UA Issues

Certificate rejected:

• Export server's certificate
• Add to trusted certificates folder
• Or use security mode: None for testing

Connection timeout:

• Verify endpoint URL
• Check firewall settings
• Confirm server is running

Modbus Issues

No response:

• Verify IP address and port
• Check unit ID matches device
• Confirm device is powered on

Wrong values:

• Check byte order settings
• Verify register addresses
• Confirm data type configuration

Network Issues

Intermittent connection:

• Check network stability
• Increase timeout values
• Review switch/router configuration

Best Practices

Security

1. Use encrypted connections (OPC UA SignAndEncrypt, MQTTS)
2. Use strong authentication
3. Isolate industrial networks
4. Keep firmware updated

Performance

1. Set appropriate polling intervals
2. Use subscriptions for OPC UA
3. Batch Modbus reads when possible
4. Monitor network bandwidth

Reliability

1. Configure automatic reconnection
2. Set up connection alerts
3. Use redundant network paths
4. Test failover scenarios

Next Steps

• Local Dashboard - View data on the edge device
• OTA Updates - Keep protocol adapters updated
• Troubleshooting - Diagnose connection issues