The JungfrauJoch broker reports packet loss during data collection as a plain
error, which fails the scan. Since 2026-09-03 that error has been suppressed on
the beamline by an uncommitted edit, through a hardcoded flag on the Eiger base
class: it applied to every Eiger at once, it could be reached neither from the
client nor from deviceConfig, and it left nothing in the log.
The tolerance is now a real parameter, raise_on_missing_packets:
- named in Eiger, Eiger9M and Eiger1_5M, so that a deviceConfig key actually
reaches the device. bec_server intersects config keys with the named
parameters of the class, so a flag reachable only through **kwargs is
silently dropped -- the same trap as readout_time (f450f29) and prefix
(10be2b5). A test pins the signatures.
- exposed through USER_ACCESS as get_/set_raise_on_missing_packets, so a
beamtime can change its mind without a redeployment. Like every runtime
value it is shared between clients and does not survive a server restart;
deviceConfig is what makes a choice stick.
- counted, and logged at warning level whenever an error is let through, so
that "which scans were affected?" has an answer. get_missing_packet_events()
returns the count.
What is tolerated is narrower than it looks: the frame-count check below still
raises when statistics.images_collected falls short of the trigger count. Only
"the broker flagged packet loss but delivered the expected number of images"
gets through, and a test pins that a short acquisition still fails.
The default stays False, i.e. tolerate, so the running beamtime is unaffected.
It should become True once the 9M's packet loss is understood, with
raise_on_missing_packets: false in that detector's deviceConfig if it still
needs it. That is one constant to change, RAISE_ON_MISSING_PACKETS.
The wording of the broker message is the only handle available, as there is no
error code for it. If JungfrauJoch rephrases it the match stops working and the
error raises again, which is the safe direction to fail in.
test_eiger_on_complete_error_message was skipped as failing "because the error
should be skipped for now due to HW issues". With the tolerance scoped to the
missing-packet message it passes again, and is no longer skipped.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Readout is a property of the detector, not a beamline constant: a 9M has more
modules than a 1.5M, and the Falcon needs 3 ms against the delay generator's
200 us. The per-model constants therefore stay, with comments saying the
duplication is deliberate so nobody consolidates them again. They all hold 2e-4
today only because no measured per-model value exists yet.
Writing a test for the deviceConfig override exposed that it never worked. Both
subclasses passed readout_time to super() while also forwarding **kwargs, so
supplying it raised "got multiple values for keyword argument" -- and through
BEC it never even got that far, because readout_time was not a named parameter
of the subclass signature and the device server drops config keys it cannot see
(the same rule behind the recent prefix incident). Both subclasses now name it
with the model constant as default, and a test asserts the signatures keep it.
Also documents frame_time_us in DetectorSettings as required-but-ignored for the
Eiger, and warns that its 500 is microseconds while every other time in the
module is seconds.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KLnmUurqcNd1FiDY5M2uZr
scan_info's exp_time is the trigger PERIOD. DDG2 gates for exp_time minus a
readout time, but the Eiger was sent the full exp_time as image_time_us, so
the detector acquired 180 us past the falling edge of its own gate and
finished only 20 us before the next trigger -- that 20 us being JungfrauJoch's
internal board-readout allowance, and the entire margin available. Measured on
a scope as a 172.8 us overhang.
Four independent notions of "readout time" existed:
500 us EIGER*_READOUT_TIME_US validation floor only, no effect on anything
200 us DDG2 DEFAULT_READOUT_TIMES["ab"] sets the gate width
20 us JungfrauJoch deployment config applied internally by JFJoch
- scan parameter readout_time honoured by the Falcon, ignored by DDG2
They are now one. DDG2 derives the gap from the scan's readout_time, floored by
its configured value (scans default it to 0), and exposes effective_readout_times().
The Eiger subtracts the same number from image_time_us. The Falcon already used
the scan value, so it needs no change.
The Eiger's 500 us constant is split in two, because it was doing two jobs: a
MIN_EXP_TIME validation floor keeps today's behaviour exactly, while the new
EIGER_READOUT_TIME defaults to 2e-4 to match the delay generator. The _US suffix
on constants holding seconds is dropped in all three modules.
Both devices log the effective exposure window at on_stage, so a period/exposure
mismatch is visible in the logs rather than only on an oscilloscope.
NOTE: this shortens the delivered exposure by the readout time -- 200 us, i.e.
0.5% at 40 ms -- for scans that do not set readout_time. Users should be told
before this is deployed.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KLnmUurqcNd1FiDY5M2uZr
menzelandClaude Opus 5
appel_c