example-mapping.json

{
  "_notes": [
    "Reference example of the edge-client mapping format. Copy to ./mapping.json and edit.",
    "Three device_type values are supported: 'master', 'slave', 'weigher'.",
    "connection.type: 'tcp' or 'rtu_serial' for Modbus, 'serial_ascii' for a scale.",
    "commands (weigher): serial commands triggered from MQTT — publish to {base}/{loc}/{name}/cmd/{key}."
  ],
  "base_topic": "acme/site",
  "poll_interval_ms": 1000,
  "devices": [
    {
      "_comment": "Main PLC — Modbus TCP.",
      "device_type": "master",
      "device_id": "plc1",
      "location": "area2",
      "name": "machine_c",
      "connection": {
        "type": "tcp",
        "host": "192.168.10.10",
        "port": 502,
        "unit_id": 1
      },
      "monitoring": [
        {
          "key": "temp_tank",
          "label": "Tank Temperature",
          "topic": "temp/tank",
          "type": "float",
          "unit": "C",
          "modbus": {
            "kind": "read_holding_registers",
            "address": 0,
            "byte_order": "big_little"
          }
        },
        {
          "key": "current_motor",
          "label": "Motor Current",
          "topic": "current/motor",
          "type": "float",
          "unit": "A",
          "modbus": {
            "kind": "read_holding_registers",
            "address": 10,
            "byte_order": "big_big"
          }
        }
      ],
      "set": [
        {
          "key": "set_temp_tank",
          "label": "Tank Temp Setpoint",
          "topic": "set/temp/tank",
          "type": "float",
          "unit": "C",
          "modbus": {
            "kind": "write_multiple_registers",
            "address": 26
          }
        }
      ],
      "control": [
        {
          "key": "control_motor",
          "label": "Motor On/Off",
          "topic": "control/motor",
          "type": "boolean",
          "modbus": {
            "kind": "write_single_register",
            "address": 6,
            "on_value": 1,
            "off_value": 3
          }
        },
        {
          "key": "control_valve_up",
          "label": "Valve Open",
          "topic": "control/valve/up",
          "type": "boolean",
          "modbus": {
            "kind": "write_single_coil",
            "address": 4
          }
        }
      ]
    },
    {
      "_comment": "Chiller slave — Modbus RTU via RS-485.",
      "device_type": "slave",
      "device_id": "slave1",
      "location": "area2",
      "name": "chiller",
      "connection": {
        "type": "rtu_serial",
        "unit_id": 8,
        "path": "/dev/ttyUSB0",
        "baud": 19200,
        "parity": "none",
        "stop_bits": 1,
        "data_bits": 8
      },
      "monitoring": [
        {
          "key": "temp_out_chiller",
          "label": "Chiller Outlet Temperature",
          "topic": "temp/out",
          "type": "integer",
          "unit": "C",
          "modbus": {
            "kind": "read_input_registers",
            "address": 1000,
            "scale": 0.1
          }
        }
      ],
      "set": [
        {
          "key": "set_temp_chiller",
          "label": "Chiller Temp Setpoint",
          "topic": "set/temp",
          "type": "float",
          "unit": "C",
          "modbus": {
            "kind": "write_multiple_registers",
            "address": 20
          }
        }
      ],
      "control": [
        {
          "key": "control_chiller_on",
          "label": "Chiller On/Off",
          "topic": "control/on",
          "type": "boolean",
          "modbus": {
            "kind": "write_single_register",
            "address": 30,
            "on_value": 1,
            "off_value": 3
          }
        }
      ]
    },
    {
      "_comment": "GSC scale — serial ASCII, non-standard digit encoding (0xB0–0xB9 = '0'–'9').",
      "device_type": "weigher",
      "device_id": "weigher_gsc",
      "location": "scale_area",
      "name": "scale_gsc",
      "connection": {
        "type": "serial_ascii",
        "path": "COM9",
        "baud": 9600,
        "parity": "none",
        "stop_bits": 1,
        "data_bits": 7
      },
      "parser": {
        "regex": "[A-Za-z-]*(?P<weight>[-+]?[0-9]+\\.[0-9]+)(?P<unit>[A-Za-z]*)",
        "byte_map": [
          {
            "from": 176,
            "to": 48
          },
          {
            "from": 177,
            "to": 49
          },
          {
            "from": 178,
            "to": 50
          },
          {
            "from": 179,
            "to": 51
          },
          {
            "from": 180,
            "to": 52
          },
          {
            "from": 181,
            "to": 53
          },
          {
            "from": 182,
            "to": 54
          },
          {
            "from": 183,
            "to": 55
          },
          {
            "from": 184,
            "to": 56
          },
          {
            "from": 185,
            "to": 57
          }
        ],
        "raw_topic": "raw"
      },
      "monitoring": [
        {
          "key": "weight",
          "label": "GSC Weight",
          "topic": "weight/raw",
          "type": "float",
          "unit": "kg"
        },
        {
          "key": "unit",
          "label": "GSC Unit",
          "topic": "unit/raw",
          "type": "string"
        }
      ],
      "commands": [
        {
          "key": "tare",
          "serial_cmd": "T\\r\\n"
        },
        {
          "key": "zero",
          "serial_cmd": "Z\\r\\n"
        },
        {
          "key": "print",
          "serial_cmd": "P\\r\\n"
        }
      ],
      "set": [],
      "control": []
    }
  ],
  "bridge": [
    {
      "read_from": {
        "device": "slave1",
        "key": "temp_out_chiller"
      },
      "write_to": {
        "device": "plc1",
        "key": "set_temp_tank"
      },
      "transform": "passthrough"
    }
  ]
}