Linux_C Language_SDK_Modbus onboard serial port and three-in-one serial port tutorial

Linux_C Language_SDK_Modbus onboard serial port and three-in-one serial port tutorial

Applicable Model

WT901C-485

HWT901B-485

SINDT-485

HWT605-485

HWT905-485

https://github.com/WITMOTION/WitStandardModbus_WT901C485

Install the wiringpi library

1. Update software repository

sudo apt-get update sudo apt-get upgrade

1. Install the wiringpi library

sudo apt-get install wiringpi If the installation is unsuccessful, switch the mirror source。 cd /tmp wget https://project-downloads.drogon.net/wiringpi-latest.deb sudo dpkg -i wiringpi-latest.deb

3. Check if the installation is successful

gpio -v

Operation steps of onboard serial port

1. View serial port mapping

ls -l /dev/ttyserial*

If the following two situations occur: Step 2 configuration is required

Case one：

Case two：

1. Map ttyAMA0 to serial0

Method one：

① Click on the raspberry logo on the top left -> Preferences ->Raspberry Pi Configuration

② Click Interfaces

③ After checking the Serial Port option, click OK

Right now：

④ Click <Yes> to restart the Raspberry Pi

Method two：

① Press and hold ctrl+Alt+T to open the terminal

② Command line input:

sudo raspi-config

• The following interface appears, select Interface Options and press Enter：

③ Select I6 Serial Port and press Enter

④ Choose<No>，press Enter

⑤Choose<Yes>，press Enter

⑥ After the following interface appears, select , and then press the Esc key to exit the page

⑦ Reboot Raspberry Pi

reboot

1. Check whether the serial port is mapped successfully

ls -l /dev/serial*

As can be seen from the above figure, serial0 is mapped to ttyAMA0 after configuration, indicating that the configuration is successful.

1. hardware connection

① Wiring problem (this example uses Raspberry Pi 3b+ as an example)

• Find the pinout diagram of the Raspberry Pi model you are using

② Wiring

• Prepare a Vitte smart sensor that supports Modbus protocol and a 485-to-TTL adapter board

1. Enter the specified folder to compile and run the program

cd ~/linux_sdk cd ./modbus gcc ./*.c -lwiringPi ./a.out /dev/ttyAMA0

1. View running results

• Prompt information and returned sensor parameter data appear

• Shake the sensor, the parameters of the sensor will be sent back and displayed in real time, indicating that the debugging is successful!

Operation steps of 3-in-1 serial port

1. Wiring

• Prepare a WitMotion sensor and 3-in-1 serial port that supports Modbus protocol

WT901C485 3-in-1

VCC <----------------------------------------> VCC

A <----------------------------------------> A

B <----------------------------------------> B

GN <----------------------------------------> GND

1. View the serial port file under the device file

ls -l /dev/ttyUSB*

Plug the 3-in-1 into the serial port of the Raspberry Pi, and enter the above command again:

ls -l /dev/tty USB* The extra serial port file is the serial port file we are looking for (ttyUSB0)

1. Enter the specified folder to compile and run the program

cd ~/linux_sdk cd ./modbus gcc ./*.c -lwiringPi ./a.out /dev/ttyUSB0

1. View running results

• Prompt information and returned sensor parameter data appear

• Shake the sensor, the parameters of the sensor will be sent back and displayed in real time, indicating that the debugging is successful!

More

For other operations, please refer to the sensor manual