dls-controls / epics_device

Framework for EPICS IOC driver implementation

EPICS Device

This is a lightweight framework for implementing record interfaces for EPICS IOCs. This framework is designed to be used in combination with the epicsdbbuilder library for building the database file, but can be used standalone.

Source code	https://github.com/dls-controls/epics_device
Documentation	https://dls-controls.github.io/epics_device

Simple Example

For example, to interface to a simple read-write register interface, the following two fragments of code will serve. This interface requires one write PV and one read PV, implemented as follows.

First the interface is implemented and published in C:

int read_register_value(void) { ... }
void write_register_value(int value) { ... }

void publish_pvs(void)
{
    PUBLISH_READER(longin, "REGISTER", read_register_value);
    PUBLISH_WRITER(longout, "REGISTER", write_register_value);
}

The corresponding database can be declared (in Python) thus:

read_reg = longIn('REGISTER', DESC = 'Register readback')
longOut('REGISTER', DESC = 'Register control', FLNK = read_reg)

With a little more code to tie things together this is a complete example. For more details see the example IOCS in the examples/ directory and the documentation in docs/.

Version 2.0

Version 2.0 introduces a major incompatibility: the mbbi and mbbo record support no longer uses RVAL but instead uses VAL with conversion disabled. This means the following changes apply:

• TYPEOF(mbbi) and TYPEOF(mbbo) have changed from unsigned int to uint16_t. This means that all code declaring records of these types will need to be changed accordingly.
• The mbbIn and mbbOut functions no longer allow the field values to be assigned: these are only meaningful for RVAL, which is now ignored.

INSTALLING

This library should be installed as a standard EPICS support package. This means that following two files in the configure directory must be edited: configure/RELEASE and configure/CONFIG_SITE.

configure/RELEASE

Change the symbol EPICS_BASE to point to your local installation of EPICS.

configure/CONFIG_SITE

This file contains a number of symbols that will need to be customised.

CROSS_COMPILER_TARGET_ARCHS

You almost certainly don't want these lines. Delete them from your version unless you know they're needed.

PYTHON

This should probably be set to python.

EPICSDBBUILDER

The python library epicsdbbuilder is a prerequisite for building and using this library.

This symbol can be in one of two formats, either an explicit path to the directory containing epicsdbbuilder or a version number understood by pkg_resources.require. Note that if an explicit path is given it is not necessary to install or setup epicsdbbuilder, it can be used in place.

See https://dls-controls.github.io/epics_device for more detailed documentation.