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ADX trend filter in an MT5 EA: wiring it from blocks, and where it breaks

mt5depot — Tue, 06 Oct 2026 12:00:28 +0000

Most trend-following ideas fail in the same quiet way: the entry rule fires in a market that is not trending. A moving average cross does not know whether the market is going somewhere or just wandering sideways. The ADX indicator was designed to answer exactly that question, which makes it a useful building block even if you never use it as the only rule.

In this post I will walk through one small, concrete example: an ADX trend EA built from blocks in the MT5 EA Builder at mt5depot. I will explain what the three ADX lines mean, show how the flow is wired, list the settings you would normally touch, and then spend a good part of the article on the part people skip: where this kind of rule breaks and how to check it before trusting it.

You can open the exact example and follow along here: https://mt5depot.com/ea-builder?template=adx_trend

Three lines, two jobs

ADX comes from Welles Wilder's 1978 book New Concepts in Technical Trading Systems. In MetaTrader 5 the indicator draws three lines from a single period setting (14 by default):

ADX (main line) measures how strong a trend is. It does not say up or down. A rising ADX means the move is getting stronger; a falling ADX means it is fading or the market is moving sideways.
+DI measures upward directional movement.
-DI measures downward directional movement.

So the lines split into two jobs. The main line answers "is there a trend at all?" The two DI lines answer "which way is it pointing?" If +DI is above -DI, buyers have had the upper hand over the lookback period. If -DI is above +DI, sellers have.

A common reading is that an ADX value above 25 suggests a trend worth following, and a value below it suggests a range. That threshold is a convention, not a law. Treat 25 as a starting point you can test, not a fact about the market.

Figure 1. ADX measures strength. The two DI lines carry the direction.

The rule we want

Written as plain sentences, the example rule is short:

If ADX is above 25 and +DI is above -DI, open a buy.
If ADX is above 25 and -DI is above +DI, open a sell.
Otherwise do nothing.

Notice that each entry needs two conditions to be true at once. That is where the AND block comes in.

Here is the rule on real prices. Under the price chart are the three lines: ADX in white, +DI in green and -DI in red, with the 25 level dashed. A mark appears on the bar where a rule's conditions turn true.

Figure 2. EURUSD H1, Sep 23 to 28, 2026, MT5 demo account price data. ADX (14) is computed with the formula of the MT5 sample ADX indicator. Marks are drawn at bar close and show where each condition turns true. This illustrates the rule; it is not a trading result.

Wiring it in the Builder

The example in the Builder has a flow of blocks running left to right.

Figure 3. The adx_trend example in the EA Builder.

Here is what each part does.

Start (OnTick). Every flow begins with a Start block, the trigger. The block is labelled OnTick, but when an entry is actually evaluated is set by the Entry timing option in the Settings tab. Its default is "Bar close - once per candle", which ignores what happens inside the candle; "Every tick" and "On touch" are the other choices. Check it before you compare the EA with a chart, because it changes how often the rule can fire.

Three ADX blocks. The same indicator block is used three times, each set to period 14 and a different line: the main line, +DI and -DI. In the Builder these show up as three separate ADX blocks, which keeps each value explicit and easy to wire.

Compare blocks. A Compare block takes two inputs and an operator. The example uses three:

ADX main compared against a threshold of 25 with the greater-than operator. This is the "is there a trend" check.
+DI against -DI, greater-than. This is the "buyers lead" check.
-DI against +DI, greater-than. This is the "sellers lead" check.

AND blocks. Two AND blocks combine the trend check with each direction check. The buy side is "ADX above 25 AND +DI above -DI". The sell side is "ADX above 25 AND -DI above +DI". Only when both inputs are true does the signal pass through.

Open Buy and Open Sell. The AND outputs feed the order blocks. The example uses a stop loss of 50 pips and a target (TP) of 100 pips on each order. These are the template's starting values, not recommendations. Both order blocks also take a lot input from a Fixed Lot block set to 0.01.

That is the whole flow: one trigger, three indicator reads, three comparisons, two AND gates, two orders and a lot size. If you can read the sentences in the previous section, you can read the diagram.

Settings you will probably touch

Besides the blocks, the Builder has a settings area for things that apply to the whole EA. For this kind of strategy, three are worth knowing about:

Lot sizing. The example uses a fixed lot of 0.01. The Builder also offers other lot modes, so you can change how position size is decided without rewiring the flow.
Filters. A spread filter lets you cap the spread at which the EA is allowed to open trades. A time filter limits the hours it may trade. Both are useful here, because trend entries that fire in thin, wide-spread hours behave differently from entries during active sessions.
Exits. A trailing stop can be switched on instead of, or alongside, a fixed target. A trend rule often benefits from letting a move run rather than cutting it at a fixed distance, though whether it does for your symbol and timeframe is something to test, not assume.

The Builder also has a Preflight check panel that flags problems in the flow before you compile. Run it. A disconnected input is much cheaper to find there than after a confusing backtest.

Where this rule breaks

Now the honest part. A rule can be correct as written and still be a poor fit for the market you point it at. Here are the weak spots of an ADX filter, so you know what to look for.

ADX lags. It is smoothed over a lookback period, so by the time it rises above 25 a trend is often already under way. The rule will tend to enter after the start of a move, not at it. That is not a bug, but it is a trade-off: you gain some confidence that a trend exists and give up part of the early move.

Whipsaws near the threshold. When ADX hovers around 25, the condition flips on and off. Combined with +DI and -DI crossing back and forth, you can get several quick entries in a row in a market that is not really going anywhere. A threshold is a sharp line drawn through a gradual change, and prices do not respect it. In Figure 2 the ADX line spends most of the window within a few points of 25 while the DI lines cross each other, which is exactly where the condition flips most easily.

Fixed stop and target distances. A 50 pip stop means very different things on different symbols and in different volatility regimes. If you move the same flow from one pair to another, or from a quiet period to a volatile one, the stop and target need rethinking. An ATR-based stop is one option to try.

Both sides can fire in turn. Because the rule has a buy side and a sell side, a market that reverses can trigger one after the other. Decide up front whether you want to allow that, or whether you want a single open position at a time.

None of this means the idea is bad. It means the example is a starting structure, and the numbers in it are placeholders you are meant to question.

Testing it properly

The MT5 Strategy Tester is where a flow like this should spend most of its time before you trust it with anything. A few habits that cost nothing:

Watch it run in visual mode first. Before looking at any summary, step through a few dozen entries and check that each one matches the sentence you wrote. If a buy fires when -DI is above +DI, the wiring is wrong, and no statistic will tell you that as clearly as seeing it.
Test more than one period. A rule that behaves well in one stretch of data and badly in another is telling you something. Run a trending period, a ranging period and a volatile one separately.
Include realistic costs. Spread and slippage matter more for rules that trade often. Set the tester to realistic spread, and do not assume the zero-cost case.
Look at the worst stretch, not the average. Check the longest run of consecutive losing trades and the deepest drop in the equity curve. Whether you can tolerate those is a better filter for a strategy than any single summary number.
Change one thing at a time. If you adjust the ADX threshold, the period, the stop and the lot all at once, you will not know which change did what. It is also an easy way to fit the settings to one stretch of history by accident.

If you tune the numbers until a single backtest curve looks good, you have mostly described that period, not the rule. Prefer settings that behave reasonably across a range of values over a single sharp peak.

Variations worth trying

Once the basic flow works and you understand it, small changes teach you a lot:

Raise or lower the ADX threshold and see how the number of entries changes.
Add a time filter so the EA only trades during the sessions you care about.
Swap the fixed target for a trailing stop.
Add a spread filter and compare behaviour with and without it.
Add a higher-timeframe condition so the EA only takes signals in the direction of a slower trend.

Each of these is a change of one or two blocks or a setting, not a rewrite, which is the main point of building from blocks: you can change the structure of an idea quickly and then let the tester tell you whether the change mattered.

Wrapping up

ADX is a good example of an indicator that is easy to misuse by itself and genuinely useful as one part of a rule: it separates "how strong" from "which way". The block diagram makes that separation visible, because the strength check and the direction check are literally different branches joined by an AND gate.

If you want to try it, the example opens directly in the Builder: https://mt5depot.com/ea-builder?template=adx_trend

Open it, read the flow against the sentences above, run it in the Strategy Tester, and break it on purpose. Knowing where a rule fails is worth more than the rule itself.

This article was drafted with AI assistance and reviewed by the mt5depot team.

How to Build a MetaTrader 5 Expert Advisor Without Writing MQL5

mt5depot — Tue, 29 Sep 2026 14:31:27 +0000

If you use MetaTrader 5, you have probably had an idea like this: "When the fast moving average crosses above the slow one and RSI is below 70, buy. Put the stop below the last swing low. Risk 1% per trade."

The idea fits in two sentences. Turning it into an Expert Advisor (EA) is a different story. MQL5 is a C++-like language with its own event model, order-handling API and quirks. For a trader or hobby developer who has never written it, the distance between "I know what I want" and "I have a file I can run in the Strategy Tester" can be weeks.

This article walks through one way to close that gap without writing MQL5 by hand: a visual, no-code builder. I work on this tool (mt5depot Builder), so I will be specific about what it does and clear about what it does not.

What an EA actually needs

Before touching any tool, it helps to write your idea down in three parts. Every EA, however complex, is some combination of these:

Entry. What condition opens a position? For example: a moving-average crossover, an RSI threshold, or a Bollinger Band breakout.
Exit. What closes it? A stop-loss, a take-profit, a break-even move, a trailing stop, or an opposite signal.
Risk. How big is the position, and what are you willing to lose on one trade? Fixed lot size, or a percentage of the account, plus any limits you want.

If you cannot state all three in plain language, no tool will save you. If you can, the rest is translation, and translation is the part a builder automates.

Step 1: Build the logic from blocks

mt5depot Builder is a visual editor that runs in your browser, so there is nothing to install. You drag blocks onto a canvas: indicators, entry and exit conditions, and risk rules. According to the product page, the block library covers stop-loss, take-profit, break-even and trailing logic as reusable components, and it shows warnings for dangerous configurations before you export.

You can also start from a strategy template instead of a blank canvas. The templates include things like moving-average crossovers, RSI reversion and Bollinger breakouts, and you adapt the blocks to your own idea.

A sensible first project is deliberately boring:

Entry: fast MA crosses above slow MA.
Exit: fixed stop-loss and take-profit.
Risk: a small, fixed position size.

Get that working end to end before adding filters. Every extra condition is another thing to test.

Designing in the editor is open to anyone. Saving projects to your account, compiling and running the strength test require signing in with a free account. Anonymous designs stay in your browser.

Step 2: Measure it before you trust it

This is the step people skip, and it is the one that matters most.

The Builder has a built-in strength test that runs your design against historical data, and a robustness matrix that evaluates it across major currency pairs. Both run in the browser, before anything touches your MetaTrader terminal.

Use them to look for problems rather than to confirm what you hope is true:

Does the design behave sensibly on more than one pair, or only on the one you tuned it for?
Does it fall apart when conditions change?
Are you seeing a handful of lucky trades or a consistent pattern?

A design that only works in one narrow setting is usually fitted to the past rather than useful going forward. If the results disappoint you, that is a cheap discovery. Change the blocks and test again.

Step 3: Export the EA

When you are happy with the design, you compile it. On the free plan you download a compiled .ex5 file, ready to load into MetaTrader 5. On the Pro plan you can also download the editable .mq5 source code, which is structured and commented so you can read it, modify it and put it under version control.

Important detail about the free plan, quoted from the product pages: a free-tier .ex5 runs only on a new MetaTrader 5 account opened through the project's partner link and approved in your account's IB tab. Pro removes that restriction, so its .ex5 runs on any account.

I would rather you know that now than discover it after building something. If you want to run the file on an account you already have, the free tier is not the right fit for that purpose, and Pro is the option that lifts the restriction.

Step 4: Load it into MetaTrader 5 and test again

The Builder's tests run in the browser on historical data. Your terminal and your broker's data are the real environment, so test there too.

In MetaTrader 5, open File > Open Data Folder, go to MQL5/Experts, and copy the .ex5 file in.
Refresh the Navigator panel (or restart the terminal). The EA appears under Expert Advisors.
Open the Strategy Tester (View > Strategy Tester), select your EA, pick a symbol, timeframe and date range, and run it.
Check the inputs the EA exposes, then compare the tester's behavior with what you designed. If trades open or close in ways you did not expect, go back to the blocks and fix the logic.

Once the tester looks reasonable, run the EA on a demo account for a while before you consider anything else. Real spreads, slippage, requotes and your broker's execution are things a historical test cannot fully reproduce.

Honest limits

A visual builder removes the syntax barrier. It does not remove the hard parts of trading.

It is a development tool, not a trading product. The Builder generates code from your design. It does not place trades, connect to a broker or supply signals or advice. What you build, test and run is your responsibility.
Backtests describe the past. Past and backtest results do not guarantee future results, and trading involves a real risk of loss. Treat test results as a way to find weaknesses, not as a promise.
You still have to think. A tool can make a bad idea easy to build. Keep positions small, test on demo first, and understand every rule your EA follows.
Plans, in short. Free: the visual editor, every strategy template, the strength test and robustness matrix, and a compiled .ex5 (with the account condition above). Pro: a one-time licence that adds the editable .mq5 source and lets the .ex5 run on any account. Pricing and current details are on the site.

Wrapping up

Turning an idea into an EA comes down to three questions (entry, exit, risk), a visual design you can adjust quickly, testing that tries to break your idea rather than flatter it, and a demo run before anything else.

If you prefer to watch the steps, there is a how-to video: mt5depot on YouTube.

If you want to try the workflow yourself, the Builder is here: Open mt5depot Builder

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