Skip to Content

SiePortal

The integrated platform for your product selection, buying and support workflow - bringing together Industry Mall and Online Support.

SiePortalDeutsch

Search

Home
Support Support
{{(apiData.Support | filter:{'rank':1}:true)[0].title}} Support
- Menu temporary not available
- Menu temporary not available
- Menue temporary not available
- {{item.title}}

Products & Services
- Menu temporary not available
- Menue temporary not available
- {{item.title}}
Support Support
{{(apiData.Support | filter:{'rank':1}:true)[0].title}} Support
- Menu temporary not available
- Menue temporary not available
- {{item.title}}
MySiePortal MySiePortal
{{(apiData.MySiePortal | filter:{'rank':1}:true)[0].title}} MySiePortal
- Menu temporary not available
- Menue temporary not available
- {{item.title}}
Cart ({{apiData.CartCount}})

Navigation

How to make an "on delay" function in SCL

Created by: kavana_z at: 2/9/2009 8:06 AM (14 Replies)

Rating (1)

Thanks 0

15 Entries

Entries per page: 10 | all

2/9/2009 8:06 AM	Rate (0)
kavana_z Posts: 5 Rating: (0)	Hello everyone, I am new to SCL and I want to make a function of "On Delay " by myself. My idea to makeitis to get the time of a certain moment and compare it with the actual system time. But i dont know how to catch the time of a certain moment. Anyone here can give me some help with this issue?
kavana_z Posts: 5 Rating: (0)
Suggestion To thank Quote Answer

2/9/2009 10:06 AM	Rate (0)
Aret Posts: 2348 Rating: (265)	You can use SFC1 for this pupose. But you will get problems if someone syncronize PLC (from SCADA for example). I would recommend OB1_PREV_CYCLE variable (TEMP variable of OB1) to get how much milliseconds last cycle was. Also there are standart timers like S_ODT (try standart help)
Aret Posts: 2348 Rating: (265)
Suggestion To thank Quote Answer

2/9/2009 11:03 AM	Rate (0)
dchartier Grandmaster Joined: 9/27/2006 Last visit: 9/4/2025 Posts: 12397 Rating: (2717)	Hello kavana_z; Here is an example of S_ODT call in SCL (On-Delay Timer) from the SCL programming manual: S_ODT (T_NO:=T10, S:=TRUE, TV:=T#1s, R:=FALSE, BI:=biVal, Q:=actFlag); You can use all SFCs, SFbs, and instructions in SCL. Hope this helps, Daniel Chartier

Suggestion To thank Quote Answer

2/9/2009 11:33 AM	Rate (0)
kavana_z Posts: 5 Rating: (0)	thank u Aret, do you have any example about how to use the temp var in OB1 for this function?
kavana_z Posts: 5 Rating: (0)
Suggestion To thank Quote Answer

2/9/2009 11:38 AM	Rate (0)
kavana_z Posts: 5 Rating: (0)	thanks Daniel, I am making an FB for some common functon, so i prefer that timers from the system not used.
kavana_z Posts: 5 Rating: (0)
Suggestion To thank Quote Answer

2/9/2009 12:50 PM	Rate (0)
Aret Posts: 2348 Rating: (265)	Sure. I put example for 1 timer - but it's easilly can be done for several timer - especially in SCL. In OB1: DB1.DBW0 := OB1_PREV_CYCLE;// DB1.DBW0 = storage to be used in programm In FB: //defining front of event IF(Event_happend AND NOT Timer_started) THEN Current_time:=0; // DINT variable, that summarizes resulting time END_IF; Timer_started := Event_happend; IF timer_started THEN IF NOT timeout_happend THEN Current_value := Current_value+WORD_TO_DINT(DB1.DBW0); END_IF; IF (Current_value > Timeout_value)ANDNOTTimeout_happend THEN Timeout_happend:= 1; // timeout happend - make some actions. END_IF; END_IF;
Aret Posts: 2348 Rating: (265)
Suggestion To thank Quote Answer

2/9/2009 1:27 PM	Rate (0)
kavana_z Posts: 5 Rating: (0)	I appreciate it very much!
kavana_z Posts: 5 Rating: (0)
Suggestion To thank Quote Answer

2/9/2009 9:01 PM	Rate (0)
andrewC Posts: 9 Rating: (0)	in case youwere building a library type of function and couldn't depend on: 1. always running in OB1 2. remembering to transfer the current runtime to a shared DB in OB1 FUNCTION_BLOCK TimeDepFunc TITLE = 'TimeDepFunc' VAR_INPUT END_VAR VAR_OUTPUT END_VAR VAR TimeStamp:TIME:=-T#24D_20H_31M_23S_647MS; // TimeStamp END_VAR VAR_TEMP currentTime:TIME; // Current time elapsedTime:TIME; // Elapsed Time END_VAR BEGIN // get current time currentTime:=TIME_TCK(); IF (TimeStamp < T#0MS) THEN elapsedTime:=T#0MS; // is first run ELSE // calc elapsed time elapsedTime:=DINT_TO_TIME(DWORD_TO_DINT(DINT_TO_DWORD(TIME_TO_DINT(currentTime-TimeStamp)) AND DW#16#7FFF)); END_IF; TimeStamp:=currentTime; // save for next run IF (elapsedTime <= T#0MS) THEN RETURN; END_IF; // add your code here END_FUNCTION_BLOCK
andrewC Posts: 9 Rating: (0)
Suggestion To thank Quote Answer

2/9/2009 9:53 PM	Rate (0)
Sydney Gold Member Joined: 1/4/2008 Last visit: 7/2/2025 Posts: 703 Rating: (98)	Hello, just 3 little things... - doubleword mask should be DW#16#7FFFFFFF - while overflow there will be inaccuracy +1ms - initial value will work only after download, not after restart when the system time is resetted to zero... (maybe the small mask could solve this, but almost 33 seconds is pretty much ) Regards Sydney

Suggestion To thank Quote Answer

2/10/2009 3:07 AM	Rate (0)
andrewC Posts: 9 Rating: (0)	Thank you, Sydney. FUNCTION_BLOCK TimeDepFunc TITLE = 'TimeDepFunc' VAR_INPUT END_VAR VAR_OUTPUT END_VAR VAR TimeStamp:TIME:=-T#24D_20H_31M_23S_647MS; // TimeStamp END_VAR VAR_TEMP currentTime:TIME; // Current time elapsedTime:TIME; // Elapsed Time END_VAR BEGIN // get current time currentTime:=TIME_TCK(); IF (TimeStamp < T#0MS) THEN elapsedTime:=T#0MS; // is first run ELSE // calc elapsed time elapsedTime:=DINT_TO_TIME(DWORD_TO_DINT(DINT_TO_DWORD(TIME_TO_DINT(currentTime-TimeStamp)) AND DW#16#7FFFFFFF)); END_IF; TimeStamp:=currentTime; // save for next run IF (elapsedTime <= T#0MS OR elapsedTime > T#1.5S) THEN RETURN; END_IF; // add your code here END_FUNCTION_BLOCK
andrewC Posts: 9 Rating: (0)
Suggestion To thank Quote Answer

2/10/2009 9:48 AM	Rate (0)
Aret Posts: 2348 Rating: (265)	Thanks, andrew, it's really nice:^) I choosed variant with OB1 because L #OB1_PREV_CYCLE T DB1.... is faster then calling SFC64 several times.
Aret Posts: 2348 Rating: (265)
Suggestion To thank Quote Answer

2/10/2009 11:49 AM	Rate (0)
dzwilu Bronze Member Joined: 12/3/2008 Last visit: 3/22/2022 Posts: 146 Rating: (4)	SFB4 may be a solution :)

Suggestion To thank Quote Answer

2/10/2009 1:42 PM	Rate (1)
Sydney Gold Member Joined: 1/4/2008 Last visit: 7/2/2025 Posts: 703 Rating: (98)	Hello to all dzwilu: I'd say it could be solution (but somebody doesn't like it) Aret: Have you ever test it? The #OB1_PREV_CYCLE is easy to use, but it's pretty inaccurate! Especially with S7-300 CPUs and short cycle. If the cycle time is less then 10ms, the deviation is such big, if it's about 100ms the deviation is smaller, but still pretty inaccurate solution. You know that the System Time (timetick) depends just on the CPU mode so monitoring of this is much better solution. Regards Sydney

Suggestion To thank Quote Answer

2/10/2009 1:48 PM	Rate (0)
Aret Posts: 2348 Rating: (265)	To be honest i never tested accuracy (i'm using this variable for analog signal smoothing, where it's not so important). My cycle time is 70-90ms. Guess it's just criteria of choise - in my case cycle time is far more important. Thank you very much for pointing out inaccuracy:^)
Aret Posts: 2348 Rating: (265)
Suggestion To thank Quote Answer

2/10/2009 2:56 PM	Rate (0)
Sydney Gold Member Joined: 1/4/2008 Last visit: 7/2/2025 Posts: 703 Rating: (98)	Aret: I thank you for the stars So the summary for the other readers, the comparation of #OB1_PREV_CYCLE and System Time (time tick with SFC64): - #OB1_PREV_CYCLE is inaccurate, but easy to use, so it can be used for the short time measuring without requirement to precise accuracy, for example forthe analog signal smoothing. - System Time monitoring is accurate, butcalling of the SFC and evaluating is more difficult and could cause a bigger load of CPU when multiple calls (longer cycle time). Use for longer time segments measuring and for accurate processing. P.S. I have tested it now again, the strange is the difference between S7-300 and S7-400. I did integration of #OB1_PREV_CYCLE value and comaration with the System Time value. The deviation is positive for S7-400 and negative for S7-300. I can't say it's a rule, I have tested it just with two CPUs, but the bad thing is that the deviation trend is continual in both cases, it means that the error is getting bigger with time. What we do in our project is the evaluation of the System Time and from it the last OB1 cycle time once at the beginning of OB1 andstore the value inDB for using anywhere in code...

Suggestion To thank Quote Answer

|

Share this page:

Share this page on...

Follow us on