No module named ‘pymodbus.client.sync‘解决方式

我的python代码使用了pymodbus库，使用时的引入如下

from pymodbus.client.sync import ModbusSerialClient as ModbusClient

后来新拿到一台设备，系统更新过，跑之前的代码一直报错

    from pymodbus.client.sync import ModbusSerialClient as ModbusClient
ModuleNotFoundError: No module named 'pymodbus.client.sync'

开始是使用pip3安装库

(GConnect-X8OCDuN_) pi@Gpm-OS:/ $ pip3 install -U pymodbus
Looking in indexes: https://pypi.org/simple, https://www.piwheels.org/simple
Requirement already satisfied: pymodbus in /home/pi/.local/share/virtualenvs/GConnect-X8OCDuN_/lib/python3.9/site-packages (3.2.2)
Collecting pymodbusUsing cached https://www.piwheels.org/simple/pymodbus/pymodbus-3.2.2-py3-none-any.whl (154 kB)Using cached https://www.piwheels.org/simple/pymodbus/pymodbus-3.2.1-py3-none-any.whl (154 kB)
Requirement already satisfied: setuptools<66.0.0 in /home/pi/.local/share/virtualenvs/GConnect-X8OCDuN_/lib/python3.9/site-packages (from pymodbus) (44.1.1)

但是依然报错，后面使用pip3 list查看了下pymodbus的版本，打印如下

pymodbus               3.2.2

又找了老板子，看到是2.5.5的，那就好办了，直接上命令

pip3 install pymodbus==2.5.5

结果又出意外

Looking in indexes: https://pypi.org/simple, https://www.piwheels.org/simple
ERROR: Could not find a version that satisfies the requirement pymodbus-2.5.5
ERROR: No matching distribution found for pymodbus-2.5.5

居然没有2.5.5版本，见鬼了，然后到pypi上去找，pymodbus · PyPI，发现真的没有，只能安装一个接近的

pip3 install pymodbus==2.5.3

顺利完成