Short summary

Name	`RTC`
→POU type	→function block
Category	IEC-block, TimerEnh
Conform to →IEC-standard	not defined in IEC-standard
Graphical interface
Available since	version 1.20.0 (for logi.CAD 3)

Functionality

This is a real-time clock.

Enter a date and time at input PT. If input IN is →turned on, output CDT returns the current date and time (starting with the date and time entered at input PT). If input IN is →turned off, the real-time clock stops, i.e. output CDT returns the last date and time. Output Q always returns the same value as the input IN.

This block receives the current system time from the runtime system. This time remains constant while the same task is executed. However, in case of different tasks, it is possible that a different system time is used when the belonging programs are executed (even if the different tasks have the same cycle time).

In-/outputs

	Identifier	→Data type	Description
Inputs:	`IN`	`BOOL`	input/start
Inputs:	`PDT`	`DATE_AND_TIME`	preset date and time
Outputs:	`Q`	`BOOL`	output
Outputs:	`CDT`	`DATE_AND_TIME`	current date and time

Input EN and output ENO are available when →calling the block. See "Execution control: EN, ENO" for information on input EN and output ENO.

See:

"Blocks for safe logic" whether this block is supported for developing safety-relevant applications.
"Highlighting safe logic in the FBD-editor" for the effects when using the block as a block for safe logic .

Example for usage within ST-editor

PROGRAM Test
    VAR
        rtc1       : RTC;
		rtc2       : RTC;
        current_dt1 : DT;
		current_dt2 : DT;
    END_VAR
    rtc1(IN := TRUE, PDT := DT#2014-09-23-10:00:00, CDT => current_dt1);
    (* Instance of block 'RTC' is called. Variable 'current_dt1' is set to current date/time starting with 2014-09-23-10:00:00 after the first call. *)
	rtc2(IN := TRUE, PDT := DT#1990-01-01-08:00:00, CDT => current_dt2);
    (* Instance of block 'RTC' is called. Variable 'current_dt2' is set to current date/time starting with 1990-01-01-08:00:00 after the first call. *)
END_PROGRAM

If the cycle time is 500 ms, the variables are set to the following date and time for the first 4 cycles :

Cycle	`current_dt1`	`current_dt2`
1	DT#2014-09-23-10:00:00.000	DT#1990-01-01-08:00:00.000
2	DT#2014-09-23-10:00:00.500	DT#1990-01-01-08:00:00.500
3	DT#2014-09-23-10:00:01.000	DT#1990-01-01-08:00:01.000
4	DT#2014-09-23-10:00:01.500	DT#1990-01-01-08:00:01.500

When creating your application within the ST-editor, enter a call of a block by typing the text as requested by the syntax or use Content Assist.