Remove python 2.7 and 3.6.

.github/workflows/ci.yml

@@ -34,12 +34,9 @@ jobs:
             runs-on: ubuntu-latest
             matrix: linux
             container:
-              2.7: docker://python:2.7-buster
-              3.6: docker://python:3.6-buster
               3.7: docker://python:3.7-buster
               3.8: docker://python:3.8-buster
               3.9: docker://python:3.9-buster
-              pypy2: docker://pypy:2-jessie
               pypy3: docker://pypy:3-stretch
           - name: macOS
             runs-on: macos-latest
@@ -51,25 +48,6 @@ jobs:
               x86: win32
               x64: win64
         python:
-          - name: CPython 2.7
-            tox: py27
-            action: 2.7
-            docker: 2.7
-            matrix: 2.7
-            implementation: cpython
-          - name: PyPy 2.7
-            tox: pypy27
-            action: pypy-2.7
-            docker: pypy2.7
-            matrix: 2.7
-            implementation: pypy
-            openssl_msvc_version: 2019
-          - name: CPython 3.6
-            tox: py36
-            action: 3.6
-            docker: 3.6
-            matrix: 3.6
-            implementation: cpython
           - name: CPython 3.7
             tox: py37
             action: 3.7
@@ -88,13 +66,6 @@ jobs:
             docker: 3.9
             matrix: 3.9
             implementation: cpython
-          - name: PyPy 3.6
-            tox: pypy36
-            action: pypy-3.6
-            docker: pypy3.6
-            matrix: 3.6
-            implementation: pypy
-            openssl_msvc_version: 2019
           - name: PyPy 3.7
             tox: pypy37
             action: pypy-3.7

README.rst

@@ -23,8 +23,7 @@ Summary
 Pymodbus is a full Modbus protocol implementation using twisted/tornado/asyncio for its
 asynchronous communications core.  It can also be used without any third
 party dependencies (aside from pyserial) if a more lightweight project is
-needed.  Furthermore, it should work fine under any python version > 2.7
-(including python 3+)
+needed.  Furthermore, it should work fine under any python version >= 3.7
 
 
 ------------------------------------------------------------
@@ -113,16 +112,13 @@ get lost in the noise: http://groups.google.com/group/pymodbus or
 at gitter:  https://gitter.im/pymodbus_dev/Lobby
 
 .. important::
-   **Note For async clients, it is recommended to use `asyncio` as the async facilitator (Python 3.6 and above).**
+   **Note For async clients, it is recommended to use `asyncio` as the async facilitator (Python 3.7 and above).**
    **If using tornado make sure the tornado version is `4.5.3`.Other versions of tornado can break the implementation**
 
 
 ------------------------------------------------------------
 Pymodbus REPL (Read Evaluate Print Loop)
 ------------------------------------------------------------
-Starting with Pymodbus 2.x, pymodbus library comes with handy
-Pymodbus REPL to quickly run the modbus clients in tcp/rtu modes.
-
 Pymodbus REPL comes with many handy features such as payload decoder 
 to directly retrieve the values in desired format and supports all
 the diagnostic function codes directly .
@@ -191,7 +187,7 @@ I get time doing such tasks as:
 ------------------------------------------------------------
 Development Instructions
 ------------------------------------------------------------
-The current code base is compatible with both py2 and py3.
+The current code base is compatible python >= 3.7.
 Use make to perform a range of activities
 
 ::

doc/INSTALL

@@ -1,8 +1,9 @@
 Requirements
 -------------
 
-* Python 2.7 or later.
-* Python Twisted, Tornado or asyncio (For async client and server)
+* Python 3.7 or later.
+* Python Twisted or Tornado (if not using asyncio for async client and server),
+remark Twisted and Tornado are in maintenance mode, and might be either dropped or supplied as plugins in the future.
 * Pyserial
 
 On Windows pywin32 is recommended (this is built in to ActivePython,