The ELOG logbook

WebDAQ can read and write the collaboration’s ELOG logbook, so a shift entry does not mean leaving run control. It is the same logbook you open in a browser — the entries are identical, whichever way you write them.

There are two logbooks in the interface and they are not the same thing:

  • Logbook → Runs — WebDAQ’s own run record: run number, times, target, voltages, accumulated charge, notes. Generated by the DAQ.

  • Logbook → ELOG — the collaboration’s ELOG server. Written by people.

1. Setting it up

Settings → ELOG.

Field

What to put in

Logbook URL

The full address as it appears in the browser, e.g. https://elog.hzdr.de/B10_alpha/.

Username / Password

One shared account for the DAQ machine. Leave empty if the logbook needs no login.

Default attributes

Fields filled into every entry — for instance Category: Shift.

Allow WebDAQ to post entries

Reading works without it; posting does not. Off until you turn it on.

Press Test connection. It reports the last entry number in the logbook if everything is right, and says what is wrong if not — a wrong password and an unreachable host give different messages.

Requirement: the server needs PSI’s py_elog package. It is not on PyPI — pip install py_elog cannot work. Install it from PSI’s conda channel:

conda activate luna
conda install -c paulscherrerinstitute elog

The Settings page says so explicitly when the package is missing.

Accounts and attribution

Authentication and attribution are separate in ELOG. The shared account authenticates the connection; the Author attribute signs the entry, and WebDAQ fills it with the username of whoever is logged into WebDAQ. Entries therefore carry a real name even though one account posts them all.

Use an account created for the DAQ, with write access to the one logbook. The password is stored in conf/elog_settings.json in plain text — the same arrangement as the Telegram token — so it should not be anybody’s personal account.

Note that py_elog does not verify TLS certificates. Traffic to an https:// logbook is encrypted but the certificate is not checked.

2. Reading

Logbook → ELOG.

The list shows the most recent entries: subject, author, date, type, and a paper clip with the number of attachments. Click one to read it on the right, with all its attributes, its full text and its attachments — pictures inline, everything else as a download. Attachments come through the WebDAQ server, because your browser has no session on the ELOG machine.

Search matches text in the entries. Clear the box to go back to the list. The list loads twenty entries at a time; Load more fetches the next twenty.

Reading does not need the Allow posting switch.

3. Writing

New entry opens the composer. The attribute fields are read from the logbook’s own entry form, so the names, the allowed values and which attributes are required are the logbook’s, not a guess — a required Category cannot be left blank here and rejected after you have written the entry.

Write up a run drafts the entry from the run itself: the timing, the beam current and accumulated charge, the regions of interest and the board configuration, assembled out of the database row, metadata.json, current.txt, stats.csv (including any stats.csv.partN) and roi.json. Everything stays editable before you post, and if some of those sources are missing for that run the toast names which — so a thin draft is never mistaken for a complete one.

  • Author is filled with your WebDAQ user; change it if you are writing for someone else.

  • Attach files with the file picker — screenshots of a spectrum, a plot, a photo of the setup.

  • Reply on an open entry threads the new one under it, keeping the shift’s attributes and prefixing the subject with Re:.

Entries are posted as plain text. An entry that was written elsewhere in HTML is shown as text here — the words are all there, the formatting is not.

4. What is worth writing

WebDAQ does not post anything by itself: nothing appears in the logbook unless a person writes it. The run record in Logbook → Runs already holds run numbers, times, charge and notes, so the ELOG entry is for what the DAQ cannot know:

  • what you changed and why — target, threshold, geometry, gas pressure;

  • what went wrong, what you did about it, and whether it worked;

  • the state of the accelerator at the start and the end of the shift;

  • a screenshot when a spectrum looks different from yesterday.

Reference the run numbers. The run record holds the numbers; the logbook holds the reasons.

5. When it does not work

Message

Cause

“The py_elog package is not installed”

Either it really is not installed — use the conda command above — or the server is running in the wrong environment. Check with lsof -ti tcp:5001 -sTCP:LISTEN | xargs ps -o command=: the interpreter must be …/envs/luna/bin/python. See Troubleshooting.

“check the ELOG user and password”

Wrong credentials, or the account has no access to that logbook.

“the ELOG server did not answer in time”

The logbook is unreachable — check the VPN. Every call gives up after 10 seconds so the DAQ is never held up by it.

“ELOG rejected the entry”

A required attribute is missing or has a value the logbook does not allow. The message repeats what ELOG said.

“ELOG posting is switched off”

Turn on Allow WebDAQ to post entries in Settings → ELOG.

“That attachment does not belong to the configured ELOG server”

The attachment proxy only fetches from the configured host.