README

sm_modbus_tcp_relay_test_1

Test state machine for the cl_modbus_tcp_relay SMACC2 client library. This state machine exercises all relay behaviors to verify proper operation.

Overview

This state machine connects to a Waveshare 8-Channel POE ETH Relay via Modbus TCP and tests all available client behaviors:

CbRelayOn - Turn on a single channel
CbRelayOff - Turn off a single channel
CbAllRelaysOn - Turn on all channels
CbAllRelaysOff - Turn off all channels
CbRelayStatus - Read channel status

State Flow

StConnect ─► StConnected ─► StRelayOn ─► StRelayOff ─► StAllOn ─► StAllOff ─► StReadStatus ─► StComplete
    ▲                           │             │           │           │            │
    └───────────────────────────┴─────────────┴───────────┴───────────┴────────────┘
                              (EvConnectionLost returns to StConnect)

State Descriptions

State	Description
`StConnect`	Waits for Modbus TCP connection to establish
`StConnected`	Connection established, transitions to relay tests
`StRelayOn`	Turns ON channel 1
`StRelayOff`	Turns OFF channel 1
`StAllOn`	Turns ON all 8 channels
`StAllOff`	Turns OFF all 8 channels
`StReadStatus`	Reads status of all channels
`StComplete`	Test complete, displays results

Configuration

Edit config/sm_modbus_tcp_relay_test_1_config.yaml:

sm_modbus_tcp_relay_test_1:
  ros__parameters:
    signal_detector_loop_freq: 20

    modbus_relay:
      ip_address: "192.168.1.254"    # Your relay board IP
      port: 502                       # Modbus TCP port
      slave_id: 1                     # Modbus slave ID
      heartbeat_interval_ms: 1000     # Connection monitoring interval
      connect_on_init: true           # Auto-connect on startup

Dependencies

cl_modbus_tcp_relay - The Modbus TCP relay client library
smacc2 - SMACC2 framework

System Dependencies

sudo apt install libmodbus-dev

Building

# Build both packages
colcon build --packages-select cl_modbus_tcp_relay sm_modbus_tcp_relay_test_1

Running

Prerequisites

Ensure the relay board is powered and connected to the network
Verify network connectivity to the relay (default: 192.168.1.254)

Manual Connectivity Test (Optional)

Before running the state machine, you can verify connectivity with mbpoll:

# Install mbpoll if not already installed
sudo apt install mbpoll

# Test connection by reading all coil states
mbpoll -m tcp -a 1 -t 0 -r 1 -c 8 192.168.1.254

Launch the Test

source install/setup.bash
ros2 launch sm_modbus_tcp_relay_test_1 sm_modbus_tcp_relay_test_1.launch.py

Expected Output

[INFO] [SmModbusTcpRelayTest1]: onInitialize
[INFO] [CpModbusConnection]: Config: 192.168.1.254:502 (slave=1, heartbeat=1000ms)
[INFO] [CpModbusConnection]: Connected to Modbus TCP device
[INFO] [StConnect]: Waiting for Modbus connection...
[INFO] [StConnect]: Connection established!
[INFO] [StConnected]: Connected! Running relay tests...
[INFO] [StRelayOn]: Turning ON relay channel 1...
[INFO] [CpModbusRelay]: Write coil 1 = ON: success
[INFO] [StRelayOff]: Turning OFF relay channel 1...
[INFO] [CpModbusRelay]: Write coil 1 = OFF: success
[INFO] [StAllOn]: Turning ON all relays...
[INFO] [CpModbusRelay]: Write all coils ON: success
[INFO] [StAllOff]: Turning OFF all relays...
[INFO] [CpModbusRelay]: Write all coils OFF: success
[INFO] [StReadStatus]: Reading relay status...
[INFO] [CpModbusRelay]: Read all coils: 0x00
[INFO] ========================================
[INFO]   cl_modbus_tcp_relay TEST COMPLETE!
[INFO] ========================================
[INFO] Test results:
[INFO]   [PASS] CbRelayOn(1) - Single channel ON
[INFO]   [PASS] CbRelayOff(1) - Single channel OFF
[INFO]   [PASS] CbAllRelaysOn - All channels ON
[INFO]   [PASS] CbAllRelaysOff - All channels OFF
[INFO]   [PASS] CbRelayStatus - Read all statuses
[INFO] State machine will remain in StComplete.
[INFO] Press Ctrl-C to exit.
[INFO] ========================================

Monitoring

State Machine Status

ros2 topic echo /sm_modbus_tcp_relay_test_1/smacc/status

State Transitions

ros2 topic echo /sm_modbus_tcp_relay_test_1/smacc/transition_log

Troubleshooting

Connection Failed

If the state machine cannot connect:

Verify network connectivity:
```
ping 192.168.1.254
```

Check firewall settings:

# Port 502 must be accessible
nc -zv 192.168.1.254 502

Test with mbpoll:

mbpoll -m tcp -a 1 -t 0 -r 1 -c 8 192.168.1.254

Check IP address in config: Ensure the ip_address parameter matches your relay board

Connection Lost During Test

The state machine handles connection loss automatically:

If connection is lost in any state, it transitions back to StConnect
The heartbeat mechanism monitors connection health every 1000ms (configurable)

Relay Not Responding

Verify slave ID: Some relay boards use different slave IDs (0, 1, 254, etc.)
Check power supply: Ensure the relay board has adequate power
Reset the relay board: Power cycle the device

Files

sm_modbus_tcp_relay_test_1/
├── config/
│   └── sm_modbus_tcp_relay_test_1_config.yaml
├── include/sm_modbus_tcp_relay_test_1/
│   ├── orthogonals/
│   │   └── or_relay.hpp
│   ├── states/
│   │   ├── st_connect.hpp
│   │   ├── st_connected.hpp
│   │   ├── st_relay_on.hpp
│   │   ├── st_relay_off.hpp
│   │   ├── st_all_on.hpp
│   │   ├── st_all_off.hpp
│   │   ├── st_read_status.hpp
│   │   └── st_complete.hpp
│   └── sm_modbus_tcp_relay_test_1.hpp
├── launch/
│   └── sm_modbus_tcp_relay_test_1.launch.py
├── src/sm_modbus_tcp_relay_test_1/
│   └── sm_modbus_tcp_relay_test_1.cpp
├── CMakeLists.txt
├── package.xml
└── README.md

License

Apache-2.0