Capture options - PandABlocks-server

This page is the canonical reference for the two distinct sets of “capture options” exposed by the server:

Field capture options — the per-field CAPTURE enumeration that selects what is captured for a pos_out field.
Connection capture options — the option line sent when connecting to the data port that selects how the captured stream is transmitted.

Field capture options¶

*CAPTURE.OPTIONS? lists the individual capture options available for pos_out fields:

Option	Description
Value	The value at the time of trigger is captured.
Diff	The difference of values is captured.
Sum	The sum of all valid values is captured (64-bit; may be scaled if `PCAP.SHIFT_SUM` is set).
Mean	The average of all valid values is captured.
Min	The minimum of all valid values is captured.
Max	The maximum of all valid values is captured.
StdDev	The standard deviation of valid values is captured. Only listed if supported by the FPGA configuration.

A field’s CAPTURE attribute can be set to No (capture disabled), to a single option, or to a space-separated combination of options (e.g. Min Max Mean).

*CAPTURE.ENUMS? returns a curated enumeration of these selections — the same list as calling *ENUMS.block.field.CAPTURE? on any pos_out field: No, Value, Diff, Sum, Mean, Min, Max, Min Max, Min Max Mean, StdDev, Mean StdDev.

These options are set per field via the field’s CAPTURE attribute — see Blocks, fields and attributes for the pos_out and ext_out capture settings, and Data capture for how capture is configured and armed.

Connection capture options¶

A line of capture options must be sent after the initial connection to the data port before any data is sent. It is a list of any of the following options separated by whitespace, ending with a newline character.

Option	Description
ASCII	Data is sent as ASCII numbers.	1	D
BASE64	Binary data is sent as a stream of base-64 strings.	1
FRAMED	Binary data is sent as a sequence of sized frames.	1
UNFRAMED	Binary data is sent as a raw stream of bytes.	1	R
SCALED	All scalable data is scaled and sent as doubles.	2	D
RAW	The captured binary data is sent without processing.	2
NO_HEADER	The data header is omitted.		R
NO_STATUS	The connection and end-of-experiment status strings are omitted.		R
ONE_SHOT	Only one experiment will be transmitted.		R
XML	The header will be sent in XML format.
BARE	Selects `UNFRAMED RAW NO_HEADER NO_STATUS ONE_SHOT`.
DEFAULT	Default options.		D

Key:

D — Default option if no other option is specified.
R — Option selected in response to the BARE option.
1 — Data transmission formats; one of these will be selected.
2 — Data processing formats; one of these will be selected.

For how these formats appear on the wire (framing, base-64 layout, header contents), see Data capture.