Demo (python):

ModbusRTU Demo

1. Project introduction

This project, via the RealMan Python development package, configures the ModbusRTU mode of the communication port, writes single coil data, reads single coil data, writes a single register, reads holding registers, and closes the communication port in ModbusRTU mode.

2. Code structure

RMDemo_ModbusRTU/
│
├── README.md        <- Core project document
├── requirements.txt    <- List of project dependencies
├── setup.py        <- Project installation script
│
├── src/          <- Project source code
│  ├── main.py       <- Main procedure entry
│  └── core/        <- Core function or business logic code
│└── demo_modbus_rtu.py<- Demo that configures the ModbusRTU mode of the communication port, writes single coil data, reads single coil data, writes a single register, reads holding registers, and closes the communication port in ModbusRTU mode.
└── Robotic_Arm/      <- RealMan robotic arm secondary development package

3. Project download

Download RM_API2 locally via the link: development package download. Then, navigate to the RM_API2\Demo\RMDemo_Python directory, where you will find RMDemo_ModbusRTU.

4. Environment configuration

Required environment and dependencies for running in Windows and Linux environments:

Item	Linux	Windows
System architecture	x86 architecture	-
python	3.9 or higher	3.9 or higher
Specific dependency	-	-

Linux configuration

1. Refer to the python official website - linux to download and install python3.9.

2. After entering the project directory, open the terminal and run the following command to install dependencies:

pip install -r requirements.txt

Windows configuration

1. Refer to the python official website - Windows to download and install python3.9.

2. After entering the project directory, open the terminal and run the following command to install dependencies:

pip install -r requirements.txt

5. Notes

This demo uses the RM65-B robotic arm as an example. Please modify the data in the code according to your actual situation.

6. User guide

6.1 Quick run

Follow these steps to quickly run the code:

1. Configuration of the IP address of the robotic arm: open the demo_modbus_rtu.py file and modify the initialization parameters of the RobotArmController class in the main function to the current IP address of the robotic arm. The default IP address is "192.168.1.18".

   # Create a robot arm controller instance and connect to the robot arm
   robot_controller = RobotArmController("192.168.1.18", 8080, 3)

2. Running via command line: navigate to the RMDemo_ModbusRTU directory in the terminal and enter the following command to run the Python script:

   python ./src/main.py

3. Running result: Upon successful execution, the running state of the robotic arm will be displayed in the terminal.

After running the script, the output result is as follows:

current api version:  0.2.9

Successfully connected to the robot arm: 1

API Version:  0.2.9

Successfully set the Modbus mode

Successfully wrote the single coil

Successfully read the coils, data: [1]

Successfully wrote the single register

Successfully read the holding registers, data: [180]

Successfully closed the Modbus mode

Successfully disconnected from the robot arm

6.2 Code description

The following are the main functions of the demo_modbus_rtu.py file:

• Connect the robotic arm

  robot_controller = RobotArmController("192.168.1.18", 8080, 3)

  Connect the robotic arm to the specified IP address and port.

• Get the API version

  print("\nAPI Version: ", rm_api_version(), "\n")

  Get and display the API version.

• Configure ModbusRTU mode.

  robot_controller.set_modbus_mode()

• Write single coil data

  robot_controller.write_single_coil(1)

• Read single coil data

  robot_controller.read_coils()

• Write a single register

  robot_controller.write_single_register(180)

• Read holding registers

  robot_controller.read_holding_registers()

• Close ModbusRTU mode

  robot_controller.close_modbus_mode()

• Disconnect from the robotic arm

  robot_controller.disconnect()

7. License information

• This project is subject to the MIT license.

8. Controller and end effector interface diagram

Controller IO Interface Diagram

The definitions of wires are explained in the following Table.

No.	First-generation cable wiring sequence	Second-generation cable wiring sequence	Definition	Description	Wire number (for second-generation cables only)	Remarks
1	Pink and brown	Black stripe brown/brown	VOUT	External output +	NO.1	12 V/24 V
2	Gray and purple	Gray/purple	P_IO_GND	External output -	NO.2
3	Yellow	Yellow	485A		NO.3
4	Yellow and green	Black stripe yellow	485B		NO.4
5	Purple and white	Black stripe white	IO1	Igital input/output bidirectional channel	NO.5
6	Red and white	White stripe red	IO2	Igital input/output bidirectional channel	NO.6
7	Green and white	Black stripe green	IO3	Igital input/output bidirectional channel	NO.7
8	Yellow and white	White stripe black	IO4	Igital input/output bidirectional channel	NO.8
9	Blue and white	Black stripe orange	OUT_P_IN	Digital power supply for external input	NO.9	0−24 V
10	Light blue	Black stripe blue	OUT_P_OUT	Digital power supply for external output	NO.10	0−24 V
11	Deep blue	Blue	OUT_P_GND	External digital ground	NO.11
12	Green	Green	FDCAN_A	CAN_H	NO.12
13	Red	Red	FDCAN_B	CAN_L	NO.13
14	White	White	Blank	Reserved	NO.14
15	Black	Black	Blank	Reserved	NO.15
16	Orange	Orange	Blank	Reserved	NO.16

Note

The voltage of digital I/O is determined based on the reference voltage connected, and the 16-core extension interface cable of robotic arm provides only 12 V and 24 V power supply voltages. If other output voltages are required for the digital I/O, then reference voltages need to be led in from the pins OUT_P_OUT+, OUT_P_IN+, and OUT_P_GND.

End Effector IO Interface Diagram

The end effector IO interface connects external tools through a 6-core aerial plug. The pins and definitions of the aerial plug are as follows.

Pin No.	Wiring color	Function
1	Yellow	RS485_A
2	White	RS485_B
3	Red	Digital interface 1 (DI1/DO1)
4	Black	Digital interface 2 (DI2/DO2)
5	Green	Power GND
6	Blue	Power output: 0 V/12 V/24 V, controllable by program

Note

The multiplexing functions in the table above are switched by program commands. Pin 3 and pin 4 are digital input channels (DI1 and DI2) by default before delivery, and the power output of pin 6 is 0 V (programmed).