How to simulate NaN (not a number) - values for testing purposes

In some cases, it is necessary to simulate NaN (not a number) values for testing purposes (f.e. if you want to test, how your business logic is able to handle such values (they could come from PLCs in case of errors).

Here is a code-sample for generating a NaN-value (-1.#QNAN0) with a Control-Script:

main()

{

blob source;

int len, pos;

string s;

float value;

s = "7F,FF,FF,FF";

source = s;

len = 4;

pos = 0;

blobGetValue(source, pos, value, len, FALSE);

DebugN(isnan(value));

//this will result into a TRUE output

dpSet("System1:TestValue.", value);

//Is some other Script is connected to this DPE, it must be able to handle this value

}