Modbus Service

Introduction

Modbus enables communication among many devices connected to the same network, for example, a system that measures temperature and humidity and communicates the results to a computer. Modbus is often used to connect a supervisory computer with a remote terminal unit (RTU) in supervisory control and data acquisition (SCADA) systems.

Many of the data types are named from its use in driving relays: a single-bit physical output is called a coil, and a single-bit physical input is called a discrete input or a contact.

Modbus Service is a Windows/Linux system service for WISE Agent to read sensor data from Modbus device or write data into Modbus device. After sensor data are acquired, WISE Agent will upload the data to the WISE-PaaS Cloud.

Modbus Service

JSON Format for upload data

{
   "Modbus_Handler":{
      "Platform":{
         "bn":"Platform",
         "e":[{"n":"Version","sv":"2.0.0"},
              {"n":"Description","sv":"This service is Modbus Service"},
              {"n":"Protocol","sv":"Modbus_TCP"},
              {"n":"Name","sv":"WISE-4012E"},
              {"n":"ClientIP","sv":"127.0.0.1"},
              {"n":"ClientPort","sv":"502"},
              {"n":"Connection","bv":true}]
      },
      "Modbus_Device0":{
         "bn":"Modbus_Device0",
         "e":[{"n":"UnitID","sv":"1"}],
         "Coils":{
            "bn":"Coils",
            "e":[{"n":"LED0","bv":true},
                 {"n":"LED1","bv":true},
                 {"n":"LED2","bv":false}]
         }
      },
      "Modbus_Device1":{
         "bn":"Modbus_Device1",
         "e":[{"n":"UnitID","sv":"2"}],
         "Discrete Inputs":{
            "bn":"Discrete Inputs",
            "e":[{"n":"Switch0","bv":false},
                 {"n":"Switch1","bv":true},
                 {"n":"Switch2","bv":false}]
         }
      }
   }
}

How To

Installation

Prerequisited packages:

1. WISE Agent

   Please download installer from EdgeSense or DeviceOn portal.

2. MQTT Broker

    You can download installer from this link: https://mosquitto.org/download/

Modbus Service Setup:

1. Double click Agent_Modbus_Handler_2.0.x.exe (Download) to start installation.

2. Click "Next" on the Welcome screen.

3. Select Installation Folder and then click "Next" to continue.

4. Click "Install" on the Ready to Install screen to continue.

5. Installation completed, click "Finish" button to exit the Setup Wizard.

Configuration

Config Modbus Connection

1. Open File Explorer and change target folder to the Modbus Service installation folder.

2. Open and edit the file Mobus_Handler.ini

2.1 Give a Name for the platform.

2.2 Set the Protocol.

Modbus TCP Connection:

Protocol=Modbus_TCP

ClientIP=(IP address of Modbus TCP devices)

ClientPort=(Port of Modbus TCP devices)  

Example:

[Platform]
Name=WISE-4012E
Protocol=Modbus_TCP
ClientIP=127.0.0.1
ClientPort=502

Interval=3
#Interval: The time interval of modbus data access/report cycle in second.
Delay=0
#Delay: The time delay between two modbus address R/W in millisecond.
#Delay=0 means no delay.
Log=0

[Devices]
numberOfDevices=2
Device0=Modbus_Device0.ini
Device1=Modbus_Device1.ini

Modbus RTU Connection:

Protocol=Modbus_RTU

SlavePort=(The serial port's device node of the Gateway which connect to Modbus RTU devices)

Baud=(The baud rate for the serial port to communicate with Modbus RTU device)

Parity=(The parity of the serial port)

DataBits=(The data bits of the serial port)              

StopBits=(The stop bits of the serial port) 

Example:

[Platform]
Name=EKI-XXXX
Protocol=Modbus_RTU
SlavePort=COM1
Baud=19200
Parity=None
DataBits=8
StopBits=1

Interval=3
#Interval: The time interval of modbus data access/report cycle in second.
Delay=0
#Delay: The time delay between two modbus address R/W in millisecond.
#Delay=0 means no delay.
Log=0

[Devices]
numberOfDevices=2
Device0=Modbus_Device0.ini
Device1=Modbus_Device1.ini

Config Modbus Devices & Sensors

1. DeviceInfo session:

    [DeviceInfo]

    UnitId: The UnitID is a device ID for a Modbus TCP device.

    SlaveID: The SlaveID is a device ID for a Modbus RTU device.

2. Coils session

    [Coils]

    NumberOfB: The number of Coils.

    Bn: The sensors definitation of Coils.

3. Discrete Inputs session

    [Discrete Inputs]

    NumberOfIB: The number of Descrete Inputs.

    IBn: The sensors definitation of Descrete Inputs.

4. Holding Registers session

    [Holding Registers]

    NumberOfR: The number of Holding Registers.

    Rn: The sensors definitation of Holding Registers.

5. Input Registers session

    [Input Registers]

    NumbrtOfIR: The number of Input Registers.

    IRn: The sensors definitation of Input Registers.

6. Coils Block session

    NumberOfBB: The number of Coils Block.

    BBn: The sensors definitation of Coils Block.

7. Discrete Input Block session

    NumberOfIBB: The number of Descrete Inputs Block.

    IBBn: The sensors definitation of Descrete Inputs Block.

8. Input Register Block session

    NumbrtOfIRB: The number of Input Registers Block.

    IRBn: The sensors definitation of Input Registers Block.

9. Holding Register session

    NumberOfRB: The number of Holding Registers Block.

    RBn: The sensors definitation of Holding Registers Block.

NOTE! The maximum length of sensor name is 30 characters.

Modbus_Device0.ini Example:

[DeviceInfo]
# For Modbus_TCP
UnitID=1
# For Modbus_RTU
#SlaveID=1

[Coils]
numberOfB=3
B0=0,LED0
B1=1,LED1
B2=2,LED2

Modbus_Device1.ini Example:

[DeviceInfo]
# For Modbus_TCP
UnitID=2
# For Modbus_RTU
#SlaveID=2

[Discrete Inputs]
numberOfIB=3
IB0=0,Switch0
IB1=1,Switch1
IB2=2,Switch2

[Input Registers]
numberOfIR=3
IR0=0,Data0,-1000000,1000000,1,V,0,""
IR1=1,Data1,-1000000,1000000,1,V,0,""
IR2=2,Data2,-1000000,1000000,1,V,0,""

Config Address and Data Types

The format and sensor address definition of sensors:

1. Single Data Format:

Tag = offset, name, min, max, precision, unit, data type, lua script

2. Block Data Format:

Block = offset, length, name

3. Tag's type, address and offset Mapping

Single Data:

Tag	Type	Address	Offset
B	Coils	00001 ~ 09999	0~9998
IB	Descrete Inputs	10001 ~ 19999	0~9998
IR	Input Registers	30001 ~ 39999	0~9998
R	Holding Registers	40001 ~ 49999	0~9998

Block Data:

Block	Type	Address	Offset
BB	Coils Block	00001 ~ 09999	0~9998
IBB	Descrete Inputs Block	10001 ~ 19999	0~9998
IRB	Input Registers Block	30001 ~ 39999	0~9998
RB	Holding Registers Block	40001 ~ 49999	0~9998

4. min and max:

    The minimal and maximal range of the sensor.

5. Precision:

    The value to denormalize a normalized sensor value become a floating point number.

6. Unit:

    The unit for the sensor value.

7. The data type definition of sensors:

Data Type	Description
0	16-bit operation
1	32-bit float no swap
2	32-bit float byte and word swap
3	32-bit float byte swap
4	32-bit float word swap
5	32-bit unsigned int no swap
6	32-bit unsigned int word swap
7	32-bit signed int no swap
8	32-bit signed int word swap

NOTE! For type of "32-bit unsigned int", the maximum support range in 0 ~ 2,147,483,647.

LUA Conversion

You can do a simple mathematic operation by add a forms in the LUA conversion string, for example:

Example1: To convert a 16-bit unsigned integer value to 16-bit signed value

[Holding Registers]
numberOfR=1
R0=0,Data0,-32768,32767,1,V,0,"(modbus_val>32767) and (modbus_val-65536) or modbus_val"

Example2: To do a mathematic forms operation.

[Holding Registers]
numberOfR=1
R0=0,Voltage0,0,5,0.001,V,0,"modbus_val*2-10"

NOTE: If both precision and LUA string are assigned, LUA string will be calculated with modbus value first, then the new value multiply with assigned precision.

LUA functions list:
https://www.kancloud.cn/thinkphp/lua-guide/43807

Docker version

To config Modbus Service and Restart Service in EdgeSense v1.0.2 Docker version:

$cd ${Installed path}/Installer/packages/Plugins/docker-edgesense-image-x86/EdgeSense/EService-Modbus/config
$sudo vim Modbus_Handler.ini
$sudo docker restart service-modbus

Release

This is an overview that displays Modbus Service versions and some stats and numbers for each release.

Index	Version	Date	Platform	OS	Release Note	Installer
1	v2.0.1	2018/9/6	x86_64 CPU	Windows	Release Note	Agent_Modbus_Handler_2.0.1.zip
2	v2.0.2	2020/7/3	x86_64 CPU	Windows	Filter out non modbus handler auto report enable request.	Agent_Modbus_Handler_2.0.2.zip

How to download:

Above files are available at local server only, please copy file's url and paste the url in File Explorer to download the file.

1. Right click on Installer file's url and copy file's url.

2. Open File Explorer and paste file's url in File Explorer.

Example:

(How to access to EOSSFS file server )