Readout Priority¶

readoutPriority is a key part of the device configuration that controls when BEC reads a device during a scan. It is independent of the ophyd Kind attribute, which controls which signals are included in those device.read() or device.read_configuration() operations. Together they determine which data will be included in scan data, configuration data or excluded.

Readout Priority Options¶

BEC supports four readout priorities that can be assigned to devices in the configuration. The most common ones are monitored and baseline, which are used for devices that should be read at monitored scan read points and baseline points, respectively. The async priority is used for devices that produce asynchronous data streams, while on_request is for devices that should only be read when explicitly requested.

Modifications during Scans¶

If the user requests to scan a motor that is not configured as monitored, the scan typically promotes it to monitored for that scan request. This ensures that scan motors are always included in monitored data, even if their static configuration differs.

Practical guidance¶

• Choose monitored for devices that should be monitored in scans.
• Choose baseline for mostly static setup-state devices and motors.
• Choose on_request for devices that should only be read when explicitly requested.
• Choose async for devices like large-area detectors that produce asynchronous data streams.