Components

Icon	Name	Description	LSP required?
FD 110	FD Tech+ 101	1-output decoder. Controls 1 valve via valve cable. No built-in LSP.	✅ Yes — within 150 m of grounded source
EasyGuard ⚡	EasyGuard	1-output decoder with built-in LSP — double-click to ground ⏚. Protects FD Tech+ 101 within 150 m when grounded.	No (has own LSP)
FD 201 ⚡	FD Tech+ 201	2-output decoder. Controls 2 valves. Built-in LSP — double-click to ground ⏚.	No (has own LSP)
FD 401 ⚡	FD Tech+ 401	4-output decoder. Controls 4 valves. Built-in LSP — double-click to ground ⏚.	No (has own LSP)
FD 601 ⚡	FD Tech+ 601	6-output decoder. Controls 6 valves. Built-in LSP — double-click to ground ⏚.	No (has own LSP)
SDI-12	SDI-12 sensor input	Sensor input on 2-Wire	❌ No
SD110	SD110 sensor input	Sensor input on 2-Wire	❌ No
CTRL/interface	Controller / Interface	System controller or interface — must connect on 2-Wire. Snaps to existing wire when placed. Always has its own dedicated ground rod (shown beneath the icon) and acts as a ground source for decoders within 150 m on the 2-Wire. Grounded decoders cannot substitute for the CTRL's ground. Used as the source for the voltage-drop calculation.	—
LSP	Lightning protection (standalone)	Standalone surge protector. Snaps to 2-Wire. Protects all decoders within 150 m.	—
V	Valve	Endpoint for valve cable — coloured by its connected decoder.	—

Cable types

Cable	Colour	Max distance	Allowed endpoints
2-Wire/monocable		150 m / 492.1 ft (LSP ↔ decoder/input)	FD Tech+ 101, EasyGuard, FD Tech+ 201 / 401 / 601, SDI-12, SD110, LSP, CTRL/interface
Valve cable		Wire-size dependent: 1.5 mm² 100 m · 2 mm² 133 m · 2.5 mm² 166 m · 16 AWG 88 m · 14 AWG 139 m · 12 AWG 220 m (auto-converted to ft in Imperial mode)	Decoder ↔ Valve only

Lightning protection rules

• FD Tech+ 101 must have a grounded source within 150 m on 2-Wire — either a standalone LSP, a grounded EasyGuard / FD Tech+ 201 / 401 / 601, or the CTRL/interface (which always has its own ground).
• EasyGuard, FD Tech+ 201 / 401 / 601 have built-in LSP and are considered grounded if they are either themselves grounded (double-click ⏚, ground rod symbol shown) or within 150 m of another ground source on the 2-Wire (green border, no rod symbol). A built-in-LSP decoder with neither is shown with a red dashed border and produces a violation.
• SDI-12 and SD110 require no LSP.
• A grounded source protects everything within 150 m measured along the 2-Wire network (not straight-line distance).
• Valve cables may be at most the maximum for the selected wire size (Size dropdown — defaults to 1.5 mm² / 100 m).
• All components must have at least one cable.
• CTRL/interface must be connected on 2-Wire.
• When at least one CTRL/interface is on the map, every decoder, input and LSP must be reachable from a CTRL via the 2-Wire graph. If no CTRL has been placed yet, components can sit unconnected (useful for sketching sub-sections before adding the controller).
• Every 2-Wire dead-end must be a standalone LSP or a self-grounded built-in-LSP decoder (EasyGuard or FD Tech+ 201 / 401 / 601 with its own ⏚). Being merely covered by another ground within 150 m is not sufficient at the termination point — the surge must be shunted to ground at the dead-end itself.

Voltage drop calculation

• System voltage: 42 V — recommended minimum at far end: 34.2 V (OK ≥ 34.2 V, warning 30–34.2 V, fail below 30 V).
• Topology auto-detected:
  • Loop: 2-Wire connects back to itself (cycle through CTRL/interface). R = (total loop length ÷ 1000) × ((Ω/km) ÷ 2). The two halves of the loop carry current in parallel for the round trip. Branch spurs off the loop add decoders to the current count but do not extend the loop length.
  • Star: 2-Wire branches outward, no return path. R = (farthest distance ÷ 1000) × Ω/km × 2. Use the radio buttons to choose worst-case (All at end) or typical (Evenly distributed — the displayed cable length is the full distance, but the calculation uses half).
• Ohm/km field: type any value, or pick a preset from the Cable preset dropdown next to it. Presets include 1.0–4.0 mm² and 10–18 AWG with their typical Ω/km values; both groups are available regardless of unit mode.
• Standby current: 0.3 mA per decoder counted on the critical path.
• Active outputs: 15 mA per active output. A fully active FD Tech+ 601 (6 outputs) draws 90 mA. Enter the total simultaneous active outputs in the Active outputs field on the Voltage-Drop bar.
• Critical-path counting: only decoders along the critical path (and any sub-branches off that path) are counted. Sibling first-level branches off CTRL/interface are ignored — their current does not flow through the critical resistance.
• Manual decoder count: override the auto count for calculation only (e.g. future-capacity planning).
• Critical path indicator: a pink overlay on the map highlights the longest 2-Wire route (Star) or the closed loop (Loop). Toggle on/off via the checkbox in the panel.
• Formula: V-drop = I × R, V@end = 42 − V-drop, must be ≥ 30 V (≥ 34.2 V recommended).
• All numeric outputs (currents, R, V-drop, V@end, distances) are shown to 1 decimal place.

End-of-2-Wire rule

• Every 2-Wire dead-end (a node with only one 2-Wire connection, excluding CTRL/interface) must be either a standalone LSP or a self-grounded built-in-LSP decoder (EasyGuard / FD Tech+ 201 / 401 / 601 with its own ⏚). The "within 150 m of a ground" allowance does not apply at a dead-end — the cable must terminate at a component that physically shunts surges to ground.

Select, copy and paste

Action	Shortcut
Select one component	Click it
Add to selection	Ctrl+click
Select multiple (drag box)	Click and drag on empty space
Select all	Ctrl+A
Copy selected	Ctrl+C
Paste (incl. internal cables)	Ctrl+V
Clear selection	Escape or click empty space
Move group	Drag any selected component

Canvas navigation

Action	Shortcut
Pan	Middle mouse button + drag — or Space + drag — or Pan button in toolbar
Zoom	Scroll wheel (pivots at mouse cursor)
Pinch zoom	Two fingers (touch screen)
Undo	Ctrl+Z — up to 50 steps
Redo	Ctrl+Y or Ctrl+Shift+Z
Set scale (any 2 points)	Set scale button → click point 1 → click point 2 → enter real distance
Measure distance	Measure button → click point 1 → click point 2 (does not change scale)
Cancel cable / clear selection	Escape
Undo last waypoint	Escape while drawing cable
Delete component	Right-click the component
Delete selection (group)	Select 1+ components and press Delete or Backspace — removes the components and any cables that touched them
Delete cable	Right-click the distance label
Ground EasyGuard or FD Tech+ 201 / 401 / 601	Double-click the component

Save, load and PDF

• Save — exports the entire layout as a JSON file (components, cables, map image, scale, voltage-calc settings, valve wire size and metric/imperial unit preference).
• Load — restores a saved layout. Supports files from V1, V2 and V3.
• Download PDF — exports the map at native image resolution with a legend, plus a voltage calculation page and any rule violations as extra pages. Distances on the PDF use the active unit mode (m / ft).
• Scale is saved in the file — distances are correct when reloaded regardless of which unit mode the file was saved in.

UI features

• Dark mode — follows your browser / OS preference automatically (prefers-color-scheme). No manual toggle needed.
• Critical path indicator — when a CTRL/interface is present, the longest 2-Wire path from CTRL/interface is highlighted on the map (the path the voltage-drop calculation uses for Star topology). Toggle on/off via the checkbox in the Voltage Drop panel (on by default).
• Validation margin — amber warnings appear when a value is within 10 % of a limit (cable length, voltage drop, etc.) so you can react before it becomes a hard violation. Red = violation, amber = early warning.
• Measure tool — read the distance between any two points without altering scale. Result stays on the canvas until cleared.
• Unit toggle — the button next to ? Help switches the whole UI between 🌐 Metric (meters) and 🇺🇸 Imperial (feet). All on-canvas distance labels, validation messages, the voltage-drop panel, the PDF export and the Set-scale prompt switch units accordingly. Both mm² and AWG cables are available in either mode (the toggle only reorders which group is listed first).
• Ohm/km presets — pick a standard cable from the dropdown to fill the Ohm/km field, or type any custom value. Available in both groups: 1.0–4.0 mm² and 10–18 AWG.
• Number precision — all calculated values are shown to one decimal place.
• Component summary — a strip above the violations lists how many of each model (FD Tech+ 101, EasyGuard, FD Tech+ 201 / 401 / 601, SDI-12, SD110) you have placed, the total decoders/inputs/CTRL count and how many ground rods or plates are on the map. Each CTRL/interface contributes its own dedicated ground; decoders contribute only if they have been explicitly grounded (double-clicked). Decoders that are merely protected through another grounded source are not counted here.
• Clickable violations — click any red error tag to pan to and briefly pulse-highlight the offending component on the map.
• Show/hide valves — the Show valves checkbox in the settings row toggles valves and valve cables on or off, useful for de-cluttering the map when reviewing the 2-Wire layout.
• Auto-connect valves — the button next to Show valves wires every unconnected valve to its nearest decoder that (a) is within the active valve-wire-size's allowed distance and (b) still has output capacity left. Use it to bulk-wire a freshly-placed cluster of valves; valves outside range or with no decoder capacity are reported in the flash message.
• Optimize 2-Wire — replaces the current 2-Wire layout with the shortest tree from the CTRL/interface that reaches every decoder, input and LSP (minimum-spanning-tree on straight-line distance). Existing 2-Wire cables and any orphaned junctions are removed; valve cables are untouched. The flash message reports the new cable count and total length. Undo with Ctrl+Z if you don't like the result.
• Component colours — every model has a distinct colour: FD Tech+ 101 and EasyGuard share light green (both 1-output siblings), FD Tech+ 201 is teal, FD Tech+ 401 is royal blue, FD Tech+ 601 is magenta. Inputs use their own palette: SDI-12 amber, SD110 violet. Valves are gray. Components always keep their original colour — when in error a small red ⚠ triangle is drawn just above the icon. The CTRL/interface is enlarged with a cyan glow, a yellow ring and its own ground rod symbol so it stands out on busy maps.
• Align & distribute — select 2 or more components (drag-box or Ctrl+click) and use the Align button group in the toolbar to line them up: left, vertical centre, right, top, horizontal centre, bottom. With 3 or more selected, the last two buttons distribute the components evenly horizontally or vertically (the leftmost/topmost and rightmost/bottommost stay put; everything in between is spaced at equal intervals).

Recent updates (V8)

• Per-segment valve cable size — the Select wire tool now works on valve cables too. Click a valve cable to open the size picker and set that segment's wire size individually (or "Use global" to follow the global valve-wire size). The distance limit is then checked per segment against its own size.
• Assign decoders without a 2-Wire — Assign decoders no longer requires a 2-Wire first. With no wire present it drops decoders next to the valve clusters (free-floating) so you can wire them up afterwards. When a 2-Wire is present it still snaps onto it.
• Auto-grounding on assign — after placing decoders, Assign decoders adds exactly the grounding needed: it grounds a minimal set of built-in-LSP decoders so everything is covered within 150 m, drops a standalone LSP only where unavoidable, and makes every 2-Wire dead-end valid (a dead-end FD Tech+ 101 becomes a grounded EasyGuard).
• Optimize 2-Wire balances drop vs cable — instead of the pure shortest-cable tree, it now picks the least-cable layout that keeps the worst decoder ≥ 30 V (or the best voltage achievable if none reaches 30 V).
• System grounding radius — any component within 150 m of a system (controller / interface / GO) is considered grounded by that system's ground rod — this also satisfies the dead-end rule.
• Active outputs — type the number freely; the value applies when you leave the field (or press Enter). It is capped at the number of valves wired to the active system shown in the Voltage Drop section.
• Voltage in violations — the far-end voltage now appears in the violations list: a warning at 25–30 V and a fail below 25 V.
• Two background maps — upload up to two maps (drag & drop, the Map button, or + Map). Each has its own opacity slider (0–100 %, 0 % hides it) and its own ✕ to remove it. Both are saved with the plan and drawn on the PDF.
• Swap a system — double-click any system (controller, interface or GO) to change its type, and a controller's station size (101 / 241 / 500).
• Clear decoders keeps the 2-Wire — removing decoders/inputs leaves the 2-Wire network intact (the removed nodes become plain junctions); only their valve/I/O cables are removed.