Question: how to log multiple Boolean transitions within one FB.

[paulbarron85]

How should one log multiple Boolean signals in the same FB? Is it ok to use the same instance or do you require a new FB for each thing you want to log. Specifically, I'm looking at the TcLogTrig. For example, can I do the following:

FUNCTION_BLOCK FB_DigitalInputLogger
VAR_INPUT
        input1 : BOOL;
        input2 : BOOL;
    fbCoreLog : REFERENCE TO TcLogCore;
END_VAR
VAR
    fbTcLogTrig : TcLogTrig;
END_VAR

fbTcLogTrig.SetLogger(fbCoreLog);
fbTcLogTrig
    .OnRisingEdge(input1)
    .Information('Input 1 is TRUE');
fbTcLogTrig
    .OnFallingEdge(input1)
    .Information('Input 2 is FALSE');

fbTcLogTrig
    .OnRisingEdge(input2)
    .Information('Input 2 is TRUE');
fbTcLogTrig
    .OnFallingEdge(input2)
    .Information('Input 2 FALSE');

[bengeisler]

You have two options:

• Use the standard logger and log OnCondition. You have to catch the rising edges yourself with R_TRIG and pass the result into the logger
• Use a single instance of TcLogTrig for each of your variables. This is necessary because it stores the state of the signal internally to detect the edges. Using it for multiple signals does not work. See the docs for an example.

You can, however, use the same instance to log one rising and one falling edge.