PRad-II HV Monitor

Real-time high-voltage monitoring and control for the PRad-II HyCal calorimeter (~1700 channels). A daemon (prad2hvd) connects to CAEN SY1527 mainframes and TDK-Lambda GEN booster supplies, polls continuously, logs faults, and serves live data to any number of browser or Qt clients via WebSocket.

Architecture

┌──────────────┐     ┌──────────────┐
│ CAEN SY1527  │     │ TDK-Lambda   │
│ HV Crates    │     │ Boosters     │
└──────┬───────┘     └──────┬───────┘
       │ TCP/IP             │ SCPI/TCP
       ▼                    ▼
┌─────────────────────────────────────┐
│          prad2hvd (daemon)          │
│                                     │
│  HVPoller thread ── poll + classify │
│  BoosterPoller thread ── poll       │
│  FaultTracker ── daily log files    │
│  WebSocket + HTTP server            │
└──────────────┬──────────────────────┘
               │ http://host:8765/
               │ ws://host:8765/
       ┌───────┼───────┐
       ▼       ▼       ▼
    Browser  Qt GUI   Scripts
    client   client   (wscat)

The daemon owns all hardware connections and makes all status decisions (fault, warning, ΔV threshold). Clients are pure displays — they read level, dv_warn, and other fields from the daemon's JSON and render them. No classification logic runs on the client.

Quick Start

# Build (daemon only, no Qt needed)
mkdir build && cd build
cmake ..
make -j$(nproc)

# Start daemon (serves both WebSocket and dashboard HTTP on port 8765)
./bin/prad2hvd

# Open in any browser
# http://localhost:8765/

Build with Qt GUI client (optional)

cmake .. -DBUILD_GUI=ON -DCMAKE_PREFIX_PATH=/path/to/Qt5/lib/cmake
make -j$(nproc)

# Run Qt client (loads dashboard from daemon's HTTP server)
./bin/prad2hvmon -H localhost -p 8765

# Save/restore settings via daemon (no GUI needed)
./bin/prad2hvmon read -s snapshot.json
./bin/prad2hvmon write -f snapshot.json

Daemon (prad2hvd)

Headless process that polls hardware, classifies channel status, logs faults, and broadcasts JSON snapshots over WebSocket.

Option	Description
-c <file>	Crates JSON (default: database/crates.json)
-m <file>	Module geometry JSON (default: database/hycal_modules.json)
-g <file>	GUI config JSON (default: database/gui_config.json)
-d <file>	DAQ map JSON (default: database/daq_map.json)
-i <file>	Error-ignore JSON (default: database/error_ignore.json)
-l <file>	Voltage limits JSON (default: database/voltage_limits.json)
-w <file>	ΔV warning rules JSON (default: database/dv_warn.json)
-r <dir>	Resources directory for HTTP serving (default: auto-discover)
-p <port>	WebSocket + HTTP port (default: 8765)
-t <ms>	Poll interval in ms (default: 2000)
-n <count>	Fault log buffer size for live display (default: 200)
-v <level>	Console verbosity: 0=silent, 1=faults only, 2=warn+fault (default: 2)

Stop with Ctrl+C. Fault logs are written to database/fault_log/YYYY-MM-DD.log continuously, whether or not any client is connected.

Fault Log Format

The daily log file is tab-separated:

2026-03-14 10:23:45.123	FAULT	APPEAR	channel	W232	ON OVC|Over Current	1523.40	1525.00
2026-03-14 10:23:45.456	WARN	APPEAR	channel	G235	ON DVW|dV warning	1402.10	1410.00
2026-03-14 10:23:48.789	FAULT	DISAPPEAR	channel	W232	ON OVC|Over Current	1524.90	1525.00

Columns: timestamp, level (FAULT/WARN), direction (APPEAR/DISAPPEAR), type, name, status, VMon, VSet. The last two columns are empty for board/booster entries. The file always records both levels regardless of -v.

Running as a Persistent Service

Use tmux to keep the daemon running after logout:

# Start in a named tmux session
tmux new-session -d -s hvd './bin/prad2hvd -v 1'

# Detach and log out — daemon keeps running

# Reattach later to check output
tmux attach -t hvd

# Detach from session (keep daemon running): Ctrl+A then D
# (clonpc19 uses Ctrl+A as the tmux prefix instead of the default Ctrl+B)

# List sessions
tmux ls

# Stop the daemon
tmux send-keys -t hvd C-c

# Force kill if unresponsive
tmux kill-session -t hvd

Qt GUI Client (prad2hvmon)

Optional thin client — a QWebEngineView window that loads monitor.html and connects to the daemon via WebSocket. No direct hardware access — all commands go through the daemon.

GUI mode (default)

Option	Description
-H <host>	Daemon hostname (default: localhost)
-p <port>	Daemon WebSocket port (default: 8765)
-r <dir>	Resources directory (default: auto-discover)

Ctrl+S saves a timestamped PNG screenshot to database/screenshots/.

CLI read/write modes

Save and restore all writable channel parameters (VSet, ISet, SVMax, etc.) via the daemon — same code path as the GUI Save/Load buttons.

# Save current settings to JSON
./bin/prad2hvmon read -s snapshot.json

# Restore settings from JSON
./bin/prad2hvmon write -f snapshot.json

# Remote daemon
./bin/prad2hvmon read -H clonpc19 -s snapshot.json
./bin/prad2hvmon write -H clonpc19 -f snapshot.json

Option	Description
-s <file>	Save output path (read mode; prints to stdout if omitted)
-f <file>	Settings file to load (write mode; required)
-H <host>	Daemon hostname (default: localhost)
-p <port>	Daemon port (default: 8765)
-t <sec>	Timeout in seconds (default: 10)

The daemon must be running. Unchanged parameters are skipped (no unnecessary hardware writes). The write command reports restored / unchanged / skipped / errors.

Web Client

The daemon serves the dashboard directly — open http://<daemon-host>:8765/ in any browser. No separate file server needed. The same port handles both HTTP (for HTML/JS/CSS) and WebSocket (for live data).

Multiple clients can connect simultaneously. All receive the same live data.

Remote Access (outside counting room)

The daemon runs on clonpc19 behind the JLab gateway. To access it from outside:

# SSH tunnel — forward port 8765 through the gateway
ssh -L 8765:clonpc19:8765 -J your_username@hallgw.jlab.org clasrun@clonpc19

Then open in your local browser:

http://localhost:8765/

For the Qt GUI client:

./bin/prad2hvmon -H localhost -p 8765

The tunnel must stay open while you use the dashboard.

Dashboard Features

• Channel Table — Sortable, filterable, live-updating. Inline VSet/ISet/SVMax/Name editing in expert mode (click ✏ to edit, Enter/✓ to apply, Escape/✕ to cancel). Bulk ON/OFF and bulk Set V on filtered channels. Summary strip with fault/warning counts.
• Save / Load — Save all writable parameters to JSON, or restore from a previously saved file. Available from the tab bar (GUI) or command line (prad2hvmon read/write). Both paths go through the daemon — same logic, same format.
• Board Status — Per-board temperature, HVMax, firmware, status.
• HyCal Geometry Map — 2D canvas at physical positions. Color by VMon, VSet, |ΔV|, or Status. Click for draggable live popups with controls.
• Booster HV Panel — TDK-Lambda GEN supply cards with live readback, VSet/ISet controls, ON/OFF. Connection managed by daemon.
• Fault Log — Live fault transition log (configurable ring buffer, default 200 entries). Colour-coded by level (FAULT/WARN) and direction (APPEAR/DISAPPEAR). Includes VMon/VSet at the moment of transition for HV channels. Unread-indicator dot on the tab.
• Alarm — Audible two-tone beep every 2s on faults. Mute toggle, auto-re-arm when faults clear.

Configuration Files

All in database/. The daemon reads them at startup and serves relevant ones to clients.

File	Used by	Purpose
crates.json	Daemon	CAEN crate addresses [{"name":"...","ip":"..."}]
hycal_modules.json	Daemon + Client	Module geometry and booster definitions
gui_config.json	Client	Display thresholds, color ranges, render interval
daq_map.json	Client	DAQ readout addresses (geo tooltips)
voltage_limits.json	Daemon	Per-pattern voltage limits (OVL fault)
error_ignore.json	Daemon	Per-channel error suppression
dv_warn.json	Daemon	Per-pattern ΔV warning thresholds

dv_warn.json example

{
    "default": 2.0,
    "rules": [
        { "pattern": "W*",       "max_dv": 2.0 },
        { "pattern": "G*",       "max_dv": 3.0 },
        { "pattern": "PRIMARY*", "max_dv": 5.0 },
        { "pattern": "*",        "max_dv": 2.0 }
    ]
}

First matching pattern wins. Same wildcard scheme as voltage_limits.json and error_ignore.json.

Dependencies

Daemon (pure C++17, no Qt):

• CMake 3.14+, C++17 compiler
• libcaenhvwrapper.so (in caen_lib/)
• Auto-fetched: nlohmann/json, fmt, websocketpp, standalone Asio

Qt GUI client (optional):

• Qt 5 (Widgets, WebEngineWidgets, WebSockets)

Author

Chao Peng — Argonne National Laboratory