Merge pull request #14 from dls-controls/documentation_update

Docs re-write, including for asyncio support

Author: coretl

README.rst

@@ -6,7 +6,7 @@ pythonIoc
 
 This module allows an EPICS IOC with Python Device Support to be run from within
 the Python interpreter. Records can be programmatically created and arbitrary
-Python code run to updated them and respond to caputs. It supports cothread and
+Python code run to update them and respond to caputs. It supports cothread and
 asyncio for concurrency.
 
 ============== ==============================================================
@@ -15,7 +15,7 @@ Source code    https://github.com/dls-controls/pythonIoc
 Documentation  https://dls-controls.github.io/pythonIoc
 ============== ==============================================================
 
-A simple example of the use of this library is the following:
+A simple example of the use of this library:
 
 .. code:: python
 
@@ -40,12 +40,12 @@ A simple example of the use of this library is the following:
             ai.set(ai.get() + 1)
             cothread.Sleep(1)
 
+
     cothread.Spawn(update)
 
     # Finally leave the IOC running with an interactive shell.
     softioc.interactive_ioc(globals())
 
-
 .. |code_ci| image:: https://github.com/dls-controls/pythonIoc/workflows/Code%20CI/badge.svg?branch=master
     :target: https://github.com/dls-controls/pythonIoc/actions?query=workflow%3A%22Code+CI%22
     :alt: Code CI

docs/conf.py

@@ -96,6 +96,7 @@
 intersphinx_mapping = dict(
     python=('https://docs.python.org/3/', None),
     cothread=("https://cothread.readthedocs.org/en/stable/", None),
+    aioca=("https://dls-controls.github.io/aioca/master/", None),
     epicsdbbuilder=(
         "https://dls-controls.github.io/epicsdbbuilder/master/", None)
 )

docs/examples/example_asyncio_ioc.py

@@ -0,0 +1,29 @@
+# Import the basic framework components.
+from softioc import softioc, builder, asyncio_dispatcher
+import asyncio
+
+# Create an asyncio dispatcher, the event loop is now running
+dispatcher = asyncio_dispatcher.AsyncioDispatcher()
+
+# Set the record prefix
+builder.SetDeviceName("MY-DEVICE-PREFIX")
+
+# Create some records
+ai = builder.aIn('AI', initial_value=5)
+ao = builder.aOut('AO', initial_value=12.45, always_update=True,
+                  on_update=lambda v: ai.set(v))
+
+# Boilerplate get the IOC started
+builder.LoadDatabase()
+softioc.iocInit(dispatcher)
+
+# Start processes required to be run after iocInit
+async def update():
+    while True:
+        ai.set(ai.get() + 1)
+        await asyncio.sleep(1)
+
+asyncio.run_coroutine_threadsafe(update(), dispatcher.loop)
+
+# Finally leave the IOC running with an interactive shell.
+softioc.interactive_ioc(globals())

docs/examples/example_cothread_ioc.py

@@ -0,0 +1,26 @@
+# Import the basic framework components.
+from softioc import softioc, builder
+import cothread
+
+# Set the record prefix
+builder.SetDeviceName("MY-DEVICE-PREFIX")
+
+# Create some records
+ai = builder.aIn('AI', initial_value=5)
+ao = builder.aOut('AO', initial_value=12.45, always_update=True,
+                  on_update=lambda v: ai.set(v))
+
+# Boilerplate get the IOC started
+builder.LoadDatabase()
+softioc.iocInit()
+
+# Start processes required to be run after iocInit
+def update():
+    while True:
+        ai.set(ai.get() + 1)
+        cothread.Sleep(1)
+
+cothread.Spawn(update)
+
+# Finally leave the IOC running with an interactive shell.
+softioc.interactive_ioc(globals())

docs/examples/example_read_from_ioc.py

@@ -0,0 +1,9 @@
+from softioc import softioc
+from cothread.catools import caget, caput, camonitor
+
+print(caget("MY-DEVICE-PREFIX:AI"))
+print(caget("MY-DEVICE-PREFIX:AO"))
+print(caput("MY-DEVICE-PREFIX:AO", "999"))
+print(caget("MY-DEVICE-PREFIX:AO"))
+
+softioc.interactive_ioc(globals())

docs/explanations/why-use-pythonIoc.rst

@@ -38,8 +38,6 @@ allows you to write this as:
     # Leave the IOC running with an interactive shell.
     softioc.interactive_ioc(globals())
 
-ADD THE CONCENTRATOR USE CASE HERE
-
 Dynamically created PVs
 -----------------------
 

docs/how-to/make-publishable-ioc.rst

@@ -0,0 +1,35 @@
+Create a Publishable IOC
+========================
+
+As seen in `../tutorials/creating-an-ioc`, a single Python script can be an IOC.
+It is also possible (and the most common situation) to have an entire Python module
+comprising an IOC. This guide explains both, as well as how to publish an IOC within
+the DLS environment.
+
+Single File IOC
+----------------
+An IOC that is entirely contained within a single Python source file can be used as an 
+IOC inside DLS simply by adding this shebang line::
+
+    #!/dls_sw/prod/python3/RHEL7-x86_64/softioc/3.0b2/prefix/bin/pythonIoc
+
+
+IOC entry point for a module
+------------------------------
+If your IOC is more complicated than one file, it is recommended to write a python 
+module (including docs/tests/etc.). The Panda Blocks Client will be an example of
+this.
+
+
+Make an IOC publishable at DLS
+------------------------------
+To make the IOC publishable, a makefile is required:
+
+``Makefile``
+    This file is necessary in order to run ``dls-release.py``, and needs to have
+    both ``install`` and ``clean`` targets, but doesn't need to actually do
+    anything.  Thus the following content for this file is enough::
+
+        install:
+        clean:
+

docs/how-to/read-data-from-ioc.rst

@@ -0,0 +1,31 @@
+Read data from an IOC
+======================
+
+This guide explains how to read data from an IOC in a separate Python program. 
+
+.. note:: 
+    Please ensure your firewall allows both TCP and UDP traffic on ports 5064 and 5065. 
+    These are used by EPICS for channel access to the PVs.
+
+
+To start, run the `cothread` IOC from `../tutorials/creating-an-ioc` or the 
+`asyncio` IOC from `use-asyncio-in-an-ioc` and leave it running at the 
+interactive shell.
+
+We will read data from that IOC using this script:
+
+.. literalinclude:: ../examples/example_read_from_ioc.py
+
+.. note::
+    You may see warnings regarding the missing "caRepeater" program. This is an EPICS tool
+    that is used to track when PVs start and stop. It is not required for this simple example,
+    and so the warning can be ignored.
+
+From the interactive command line you can now use the ``caget`` and ``caput`` functions to operate on 
+the PVs exposed in the IOC. Another interesting command to try is::
+
+    camonitor("MY-DEVICE-PREFIX:AI", lambda val: print(val))
+
+
+You should observe the value of ``AI`` being printed out, once per second, every time the PV value
+updates. 

docs/how-to/use-asyncio-in-an-ioc.rst

@@ -1,4 +1,33 @@
 Use `asyncio` in an IOC
 =======================
 
-Write about the differences creating an IOC using `AsyncioDispatcher`
+There are two libraries available for asynchronous operations in PythonIOC:
+`cothread` and `asyncio`. This guide shows how to use the latter in
+an IOC.
+
+.. note::
+    This page only explains the differences between using `cothread` and `asyncio`.
+    For more thorough explanation of the IOC itself see `../tutorials/creating-an-ioc`
+
+.. literalinclude:: ../examples/example_asyncio_ioc.py
+
+
+The ``dispatcher`` is created and passed to :func:`~softioc.softioc.iocInit`. This is what 
+allows the use of `asyncio` functions in this IOC. It contains a new event loop to handle
+this.
+
+The ``async update`` function will increment the value of ``ai`` once per second,
+sleeping that coroutine between updates.
+Note that we run this coroutine in the ``loop`` of the ``dispatcher``, and not in the
+main event loop.
+
+This IOC will, like the one in `../tutorials/creating-an-ioc`, leave an interactive 
+shell open. The values of the PVs can be queried using the methods defined in the 
+`softioc.softioc` module.
+
+
+Asynchronous Channel Access
+---------------------------
+
+PVs can be retrieved externally from a PV in an asynchronous manner by using the :py`aioca` module. 
+It provides ``await``-able implementations of ``caget``, ``caput``, etc. See that module for more information.

docs/index.rst

@@ -59,6 +59,8 @@ Table Of Contents
     :maxdepth: 1
 
     how-to/use-asyncio-in-an-ioc
+    how-to/make-publishable-ioc
+    how-to/read-data-from-ioc
 
 .. toctree::
     :caption: Explanations