read-data-from-ioc.rst

Read data from an IOC

This guide explains how to read data from an IOC in a separate Python program.

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.

Using Channel Access

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.

We will read data from the IOC using this script:

.. literalinclude:: ../examples/example_read_from_ioc_ca.py

You can run this as:

python -i example_read_from_ioc_ca.py

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", print)

You should observe the value of AI being printed out, once per second, every time the PV value updates.

Using PVAccess

Note

Please ensure your firewall allows both TCP and UDP traffic on ports 5075 and 5076. These are used by EPICS for PVAccess to the PVs.

We will read data from the IOC using this script:

.. literalinclude:: ../examples/example_read_from_ioc_pva.py

You can run this as:

python -i example_read_from_ioc_pva.py

From the interactive command line you can now use the ctx.get and ctx.put functions to operate on the PVs exposed in the IOC. Another interesting command to try is:

ctx.monitor("MY-DEVICE-PREFIX:AI", print)

You should observe the value and timestamp of AI being printed out, once per second, every time the PV value updates.