epics-device-support

To implement EPICS device support for an ai record, define an init_record function to parse the INP link and a read_ai function to handle hardware reads, then map these functions into a device support entry table (dset) exported from your support module.

Asynchronous I/O in EPICS device drivers uses the PACT flag to manage non-blocking read and write operations, allowing the record processing to yield and resume later when hardware communication finishes via callback-driven record reprocessing.

I/O Intr scanning triggers EPICS record processing through event-driven updates, where your device driver uses safe callbacks to reprocess records only when new hardware data arrives, rather than relying on periodic timed scanning.

You register custom device support and IOC shell commands in EPICS by publishing device support choices via DBD declarations and registering configuration commands and variables for use in st.cmd, ensuring correct epicsExport include ordering.

A dset table in EPICS is a structure of function pointers that connects database record types like ai, ao, and waveform to your custom hardware driver logic. You need it whenever you integrate new hardware with EPICS database records.

EPICS device support callbacks cause record processing issues when return-value conventions are ignored or dpvt private data is improperly initialized, leading to unsafe callback-driven record reprocessing during non-blocking operations.