How to Attach an EA to a Chart in MT5 (with input tuning)

Instructions étape par étape

1. Étape 1 : Open the right chart first

   Before dragging an EA onto a chart, make sure the chart matches the EA's expected configuration. The two parameters that matter are the symbol (EURUSD, XAUUSD, etc) and the timeframe (M1, M5, H1, etc).

   In Market Watch (Ctrl+M), right-click the symbol → 'New Chart' if you don't already have it open. Switch to the timeframe via the toolbar buttons (M1, M5, M15, H1, H4, D1, MN). Most EAs are documented for a single timeframe; running off-timeframe usually still works but produces different signal counts and stop sizes than the vendor's published backtests.

   If the EA trades multiple symbols (rare; usually 'multi-pair' EAs use a master chart), the documentation will specify which chart to attach. Default: one EA, one chart, one symbol.

2. Étape 2 : Drag the EA from Navigator

   Open Navigator (Ctrl+N). Expand 'Expert Advisors'. Find your EA in the list — it shows with a small grey icon. Drag the icon directly onto the chart.

   The chart's title bar updates to show the EA name in brackets, e.g. 'EURUSD,M5 [MyEA]', and a popup opens with the EA's configuration tabs. If no popup appears, MT5 was already showing it for a previous attempt — check behind the main window.

   If you accidentally drop the EA onto the wrong chart, just drag the correct EA onto the correct chart later. MT5 limits one EA per chart but multiple charts per terminal.

3. Étape 3 : Configure the Common tab

   The Common tab has three sections: Position management, Live trading, and Magic Number override.

   Under Position management, leave 'Long & Short' selected unless the vendor specifies otherwise (some grid EAs are direction-restricted). Under Live trading, tick 'Allow live trading' — without this the EA runs in read-only mode and never sends orders. Tick 'Disable auto-trading when the account has been changed' as a safety guard against accidental live execution after switching to a demo account.

   'Allow modification of signal settings' is needed for EAs that copy from MQL5 Signals; safe to leave on. The 'Magic Number override' is the most important field for multi-EA setups: it forces a specific Magic regardless of what the EA's internal default is. If you run two copies of the same EA on different symbols, use the override to ensure each copy has a unique Magic.

4. Étape 4 : Configure the Inputs tab

   Switch to the Inputs tab. This shows every configurable parameter the EA exposes, with the EA's compiled-in defaults as starting values.

   Click the 'Load' button at the bottom and pick the vendor's .set preset from MQL5\Presets\. The values update across the board. Important: the .set file overrides every parameter it defines and leaves anything new (added in a later version) at default. If you see warnings in the Experts log later like 'Unknown parameter X', the .set is from a different EA version.

   Review risk-related inputs even after loading a preset. Lot Size, Risk Percent, Max Drawdown, and Daily Stop Loss should be calibrated to your actual account balance. A preset designed for a $10,000 account on a $1,000 account will trade 10× larger than intended. Adjust before clicking OK.

5. Étape 5 : Check the Dependencies tab (if it appears)

   Some EAs use custom indicators or other resources. If the EA depends on a custom indicator file, the Dependencies tab appears next to Inputs and lists each required resource with its file path.

   Green ticks mean MT5 found the resource. Red crosses mean it is missing — copy the indicator .ex5 into MQL5\Indicators\ and refresh the Navigator. The popup needs to be closed and re-opened to re-check dependencies; there is no 'refresh' button on this tab.

   If the EA cannot run without a missing dependency, OnInit will fail when you click OK and the chart will show a red sad face with 'EA could not be initialised' in the tooltip. Read the Experts log to confirm which resource was missing.

6. Étape 6 : Save the chart as a template

   Click OK to close the popup. The EA is now attached. Verify the green smiley appears top-right of the chart.

   Right-click the chart → Template → Save Template. Give it a name like 'MyEA-default-EURUSD-M5.tpl'. Templates store: chart symbol, timeframe, indicators, EA attachment with all inputs, and visual styling. Loading a template via Template → Load applies everything in one click.

   This matters because MT5 sometimes detaches EAs after reconnect or account change. Having a saved template lets you re-attach in seconds rather than redoing the whole configuration. Many traders save one template per EA per account and store them all in the data folder's templates/ sub-directory.

Erreurs courantes à éviter

• ✗ Two EAs with the same Magic Number on different chartsSolution: Use Common tab → Magic override to assign each EA-chart pair a unique integer. Otherwise they read each other's positions.
• ✗ Leaving 'Allow live trading' untickedSolution: Even with global AutoTrading on, per-chart trading off means the EA cannot place orders. Both must be green.
• ✗ Loading a .set from a different EA versionSolution: MT5 silently drops mismatched lines. Always source the .set from the same vendor release as the .ex5.
• ✗ Not saving the chart templateSolution: If MT5 restarts or you switch accounts, the EA may detach. Saved templates restore the entire setup in one click.

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