ModBus smartCORE module

Description

The "modbus" module primarily reads the ModBus registers of ModBus devices. These devices can be

• via a serial connection (ModBus/RTU)
• via TCP (ModBus/TCP)

be connected.

Interfaces & protocols used

• ModBus

JSON configuration

The following section describes the entire JSON configuration of the module and explains the individual parameters.

Example configuration

An example ModBus/TCP configuration is shown below:

    {
      "module": "ModBus",
      "comment": "ModBus/TCP config",
      "factory": "modbus",
      "config": {
        "version": 1,
        "type": "modbus",
        "enable": true,
        "pollCycleInMilliseconds": 1000,
        "transport": {
          "type": "tcp",
          "ipAddress": "192.168.0.1",
          "ipPortNumber": 502,
          "timeoutInMilliseconds": 200
        },
        "devices": [
          {
            "enable": true,
            "deviceName": "Device Name",
            "deviceAddress": 1,
            "readChannels": [
              {
                "name": "Channel Name",
                "address": 49152,
                "registerType": "HoldingReg",
                "registerFormat": "REAL",
                "byteOrder": "ABCD",
                "bitOffset": 0,
                "unit": "",
                "scale": 1.0,
                "offset": 0.0
              }
            ]
          }
        ]
      }
    }

Global module parameters

Parameter name	Required	Data type	Meaningful value range	Default	Description
version	YES	INT	1	-	ModBus protocol version
type	YES	STRING	"modbus"	-	Serial interface for communication
enable	YES	BOOL	true	-	Switch for production of data in smartCHANNELs
pollCycleInMilliseconds	YES	INT	1 -	-	polling interval [ms] of ModBus accesses
transport	YES	JSON object		-	configuration of the ModBus transport layer (see below)
devices	YES	JSON array of JSON objects		-	List of ModBus participants

ModBus/TCP specific transport parameters ("transport")

Parameter Name	Required	Data Type	Meaningful Value Range	Default	Description
type	YES	STRING	"tcp"		Selection ModBus/TCP
ipAddress	YES	STRING	Valid IP address		IP address of the ModBus device
ipPortNumber	YES	INT	Valid IP port number		IP port number of the ModBus device (should be set to 502 unless otherwise specified)
timeoutInMilliseconds	YES	INT	1 -		Timeout [ms] for TCP connection (should be set to 200 unless otherwise specified)

ModBus/RTU specific transport parameters ("transport")

Parameter name	Required	Data type	Meaningful value range	Default	Description
type	YES	STRING	"rtu"		Selection ModBus/RTU
baudRate	YES	INT	Valid ModBus baud rate		Baud rate of the serial interface
dataBits	YES	INT	5 - 8		Data bits of the serial interface
encoding	YES	STRING	"rtu"		Encoding of the ModBus data (only "rtu" is supported)
parity	YES	STRING	"no", "even", "odd"		Parity of the serial interface
stopBits	YES	DOUBLE	1.0, 1.5, 2.0		Stop bits of the serial interface
portName	YES	STRING	Valid device file		Device file of the serial interface
terminationResistor	YES	BOOL	true, false		Switch for INTERNAL termination resistor
timeoutInMilliseconds	YES	INT	1 -		Timeout [ms] for TCP connection (should be set to 200 unless otherwise specified)
deviceTimeoutInMilliseconds	No	INT	0 -	0	Additional timeout [ms] between the queries of different ModBus participants

ModBus device parameters ("devices")

Parameter Name	Required	Data Type	Meaningful Value Range	Default	Description
enable	YES	BOOL	true		Switch for activating the ModBus device
deviceName	YES	STRING			Name of the ModBus device
deviceAddress	YES	INT	1 -		Address of the ModBus device
readChannels	YES	JSON Array of JSON objects			see below

ModBus channel configuration ("readChannels")

Parameter name	Required	Data type	Meaningful value range	Default	Description
name	YES	STRING			name of the smartCHANNEL
address	YES	INT			Address of the ModBus register
registerType	YES	STRING	Valid ModBus register type		Type of ModBus register ("InputReg", "HoldingReg", "Coil", "Status", "0x17" (read access only))
registerFormat	YES	STRING	Valid ModBus register format		Format of the ModBus register ("I8", "I16", "I32", "I64", "UI8", "UI16", "UI32", "UI64", "REAL", "BOOL")
byteOrder	YES	STRING			Byte order of the ModBus register ("A" = MSB, "B" or "D" = LSB)
bitOffset	YES	UINT			Bit offset of the value to be interpreted
unit	YES	STRING			Unit of the smartCHANNEL
scale	YES	DOUBLE			Scaling of the smartCHANNEL
offset	YES	DOUBLE			Offset of the smartCHANNEL

ModBus channel configuration ("readChannelGroups")

Alternatively, several channel configurations can be combined into a JSON array, so that the ModBus registers on which this group is based can be read in a single step can be read in a single step (if the register type is identical). This readChannelGroup array combined in this way can then be listed in the JSON array of the "readChannelGroups", e.g.

"readChannelGroups": [
  [
    {
      "name": "Channel 1",
      "address": 49152,
      "registerType": "HoldingReg",
      "registerFormat": "REAL",
      "byteOrder": "ABCD",
      "bitOffset": 0,
      "unit": "",
      "scale": 1.0,
      "offset": 0.0
    },
    {
      "name": "Channel 2",
      "address": 49158,
      "registerType": "HoldingReg",
      "registerFormat": "REAL",
      "byteOrder": "ABCD",
      "bitOffset": 0,
      "unit": "",
      "scale": 1.0,
      "offset": 0.0
    }
  ]
]

Alternatively, "readChannels" or "readChannelGroups" can be specified.

Module information

Information	Value
Authors	optiMEAS Measurement and Automation Systems GmbH
since smartCORE	0.1
Module type	Producer
Dependencies	NONE