Dear experts,

Am using CPU 416-2DP , I need to compare the PLC time and enable an output, is it possible in Simatic manager Step-7 v5.4.

For eg: Every day i need to reset a counter value @ 6:00 am.

Hi

Sketch of the program:

Local TEMP Variables in the FC [from beginning L0.0]

DateTime: DATE_AND_TIME // Date And Time

mmss : Bool; // Minutes = Seconds = 0

Shift1 : Bool; // Bit equal to 1 when system time = 06:00:00

Shift2 : Bool; // Bit equal to 1 when system time = 14:00:00

Shift3 : Bool; // Bit equal to 1 when system time = 22:00:00

RTC_RESULT: Int // Result of SFC

1. Call SFC1 READ_CLK and get system time as date_time

      CALL  "READ_CLK" // SFC1
       RET_VAL:=#RTC_RESULT
       CDT    :=DateTime

2. Check if minutes = seconds = 00

A(

L LB4 // Minutes

L 0 // Minutes=0

==I

)

A(

L LB5 // Seconds

==I

)

=mmss // minutes = seconds = 0

3. compare byte for hour and check if minutes=seconds=0

// 06:00:00

A(

L LB3 // Hours

BTI // BCD To Integer

L 6 // Hours when shift changes

==I

)

A mmss

= Shift1

//14:00:00

A(

L LB3 // Hours

BTI // BCD To Integer

L 14 // Hours when shift changes

==I

)

A mmss

= Shift2

// 22:00:00

A(

L LB3 // Hours

BTI // BCD To Integer

L 22 // Hours when shift changes

==I

)

A mmss

= Shift3

4. Use bits Shift1, Shift2, Shift3 to do Your reset operations.

NOTE: These bits are true for about one second (accuracy: Your OB1 Scan Time)

ms are ignored because scan will not be at exact 000ms

You can modify code for different shift patterns.

Should You need compare minutes / seconds against non-zero values

You need convert them from BCD to INT (use BTI instruction)

@hdhosseini and Piotr.M 

Thank you so much.

It was very helpful. 

Is it possible to calculate the time for, how long an output was in on condition.

i.e I need to measure the running hours of an motor, using its run feedback.

is there any SFC to measure the run hours.

Hi

You could do the following:

1. use PLC CPU runtime counters (limited amount)

OR

2. program a one shot bit which is triggered at desired resolution (100ms or 1s or whichever)

and on that pulse increment a dint variable when item is running,

You can have both TOTAL (non-resettable) and resettable runtime counter (resettable could be

cleared when maintenance is done to remind crew about next scheduled maintenance).

New question published by Elhamdi is split to a separate thread with the subject Need to compare two variable type time.

Best regards
Jen_Moderator