Modbus API reference

{
    "result": {},
    "requestId": "00000007",
    "errorCode": 0,
    "errorMessage": ""
}

{
  "result": {},
  "requestId": "00000011",
  "debugInfo": {
    "request": {
      "api": "hub",
      "action": "createInput",
      "params": {
        "inputName": "modbusTCP",
        "serviceName": "modbus",
        "settings": {
          "modbusProtocol": "TCP",
          "modbusServer": "127.0.0.1",
          "modbusServerPort": 1505,
          "propertyMapList": [
            {
              "propertyPath": "temperature",
              "modbusDataAddress": "holdingregister",
              "modbusDataAddress": 1199,
              "modbusUnitId": 5,
              "modbusDataLen": 1
            }
          ]
        },
        "tableName": "modbusTableTCP"
      },
      "requestId": "00000011",
      "debug": "max",
      "authToken": "replaceWithAuthTokenFromCreateSession"
    }
  },
  "errorCode": 12012,
  "errorMessage": "There is already an integration with name of [modbusTCP].",
  "authToken": "replaceWithAuthTokenFromCreateSession"
}

The "bitBooleanZeroValue" property is optional and defaults to false. It applies when the "modbusDataType" property is set to "bitBoolean". When set to true, the connector maps a bit value of 1 to false and 0 to true.

The "bitEndPosition" property is a zero-based bit position with a value from 0 to 15. It is required only when the "modbusDataType" property is set to "bitInt" or "bitEnum". When present, it must be greater than or equal to "modbusStartBitPosition". When omitted, it defaults to the value of the "bitStartPosition" property.

The "bitEnumValues" property is an array of JSON values, each typically a JSON string. It is required only when the "modbusDataType" property is set to "bitEnum".

The "bitIntSigned" property is optional and defaults to false. It applies when the "modbusDataType" property is set to "bitInt". When set to true, the connector interprets the bits as a signed integer.

The "bitLittleEndian" property is optional and defaults to false. It applies when the "modbusDataType" property is set to "bitInt" or "bitEnum". When set to true, the connector interprets a range of nine or more bits in little-endian order instead of big-endian order. A range of eight bits or less is unaffected by endian status. The Modbus "int16SignedBA" or "int16UnsignedBA" data types are in little-endian order.

The "bitReverseOrder" property is an optional Boolean value. It applies when the "modbusDataType" property is set to "bitInt" or "bitEnum". When true, the connector assigns bit values to the integer value starting from the end bit position to the start bit position; otherwise, it starts with the start bit position. It places bit values into the integer, starting from the rightmost bit to the leftmost.

For example, if "bitReverseOrder" is false, "bitStartPosition" is 5, and "bitEndPosition" is 6, the connector works its way from the end position to the starting position, setting bits in the integer from right to left. For example, it takes the bit value at the bit end position and sets it into the rightmost bit in the integer. It then takes the bit value at the next-to-last position and sets it to the left of the previous bit. Thus, if 1 is the bit value in the Modbus register at bit position 5 and 0 is the value of bit position 6, the resulting binary integer value is 0000 0010. Given the same bit values, if "bitReverseOrder" is true, the resulting integer value is 0000 0001.

The "bitStartPosition" property is a zero-based bit position with a value from 0 to 15. It is required when the "modbusDataType" property is set to "bitBoolean", "bitString", "bitInt", or "bitEnum".

The "bitStringOneValue" property is a string and is required when the "modbusDataType" property is set to "bitString". When the bit value is 1, the connector assigns the value of "bitStringOneValue" to the JSON key defined by "propertyPath". You may set it to any string value, including the empty string "", "null", "true", "false", "2", or "-9". You cannot set it to a non-string value, such as the JSON symbols null, true, false, or a number like 2, or -9.

The "bitStringZeroValue" property is a string and is required when the "modbusDataType" property is set to "bitString". When the bit value is 0, the connector assigns the value of "bitStringZeroValue" to the JSON key defined by "propertyPath". You may set it to any string value, including the empty string "", "null", "true", "false", "2", or "-9". You cannot set it to a non-string value, such as the JSON symbols null, true, false, or a number like 2, or -9.

Define the word size and its type (read-only or read-write).

The  "modbusDataAddress" property specifies where the Modbus protocol should read or write a value to a memory address on a device. By default it is zero-based and ranges from 0 to 65,535.

Some vendors document data addresses as one-based values. Set the "modbusDataAddressType" to "oneBased" to configure the "modbusDataAddress" property to use a one-based address, which ranges from 1 to 65,536.

For more detailed information about the "modbusDataType" property, read our documentation on Modbus data types.

The "propertyPath" property is a required string that specifies the JSON Path in the JSON document where the connector puts the data it collects. It is the tag name of the data being collected. You can use this property to take collected data and store it in any location in the JSON document generated by the connector. For example, the setting "propertyPath": "temperature" causes the server to take a value it collects, such as 20.1, and store it in a "temperature" property, such as { "temperature": 20.1 }.