How to communicate between two EAs?

Hi,

How do I communicate between two EAs attached to different charts?

I want one EA to be able to read the value of a variable in another EA

The simplest way to do this is with global variables. You set the variable in one or more EA and it can be read by all others. I have read other postings stating that globals involve a lot of overhead; the way I have used them avoids that issue. The trick is to know when the variable has changed and that depends on how it is to be used, so you need to figure that out.

Check out GlobalVariableSet() in the documentation - it is very simple.

hey thats very interesting information - so can u more specifically talk about how it works - i mean is it really as simple as using GlobalVariableSet() in one EA and GlobalVariableGet() in the other ?

thx

well thats weird - the value has to be a double !?!


GlobalVariableSet(string name, double value)

What would be the actual code to write in one EA, and in another EA to read the global variable?

Pipmyride,

What other data types would you like / need ? Strings ?

I've got a pretty good idea that getting around this limitation would incur a fair bit of coding and knowledge.

well basically one EA has shapes on the chart that it needs to send to the 2nd EA - so we have a price and time point - a double and a datetime to pass over

Datetime is stored as 4 byte integer in mql4. Double is stored in 8 bytes. The range of a 4 byte integer is from -2147483648 to 2147483647, which should fit quite comfortably in an 8 byte double.

So you can cast the datetime to a double to save as a globalvariable and then back to a datetime when you read it. As long as you don't perform any operations on it while it is a double, it should be fine.

What would I need to do for the following scenario:

1. The flag "TradeTakeOver" in EA1 has been changed to true.

2. EA2 reads the flag in EA1 and does not open any more orders.

How do I code the above two things in the respective EAs?

1) GlobalVariableSet(TakeOver,1);

2) if(GlobalVariableGet(TakeOver)==1 && b==c && ...){SendOrder(...);}

THANKS!

Something is wrong, it is not working.


GlobalVariableSet(TakeOver,1);

if (GlobalVariableGet(TakeOver) == 1)
{
TradeTakenOver = true;
}

Comment(TradeTakenOver);


TradeTakenOver should show as 1 but it still shows as 0.