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TOD to start and stop a function ?

Created by: Illum at: 1/26/2009 10:47 PM (8 Replies)

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1/26/2009 10:47 PM	Rate (0)
Illum Posts: 4 Rating: (0)	Hi I'm looking for some help to make a function start and stop again onspecific times (08.00 and 18.00 every day). The start and stop time wil be set in 2 different fields in a panel (TP177B) I know how to program the panel. But look for some help to the S7 program. Best regards Illum
Illum Posts: 4 Rating: (0)
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1/26/2009 11:20 PM	Rate (0)
Phantom75 Posts: 2661 Rating: (279)	Hi, You can do this by using SFC1:READ_CLK. Compare the system time with the time fields in your Simatic Panel and conditionally process your function. The following FAQ explains how to use the SFC1: How can you read out the date and time with SFC1 (READ_CLK) and input them with SFC0 (SET_CLK)? Regards
Phantom75 Posts: 2661 Rating: (279)
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1/28/2009 12:35 PM	Rate (0)
dzwilu Bronze Member Joined: 12/3/2008 Last visit: 3/22/2022 Posts: 146 Rating: (4)	Simply use the time_of_day interrupt in your CPU configuration. Best regards dzwilu

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1/28/2009 7:23 PM	Rate (0)
Phantom75 Posts: 2661 Rating: (279)	dzwilu . . . use the time_of_day interrupt in your CPU configuration. . . . That's one way of doing it... But to make yourTime-of-Day interrupt dynamic (settable fromI/O field on TP), you need to use SFC's 28 to 31. Care should be taken before and after warm restart or cold restart because the time-of-day interrupt settings made by the SFC's are cleared and the default setting in HW config becomes effective! Also,problems could arise if you shift the clock during day light savings... Regards
Phantom75 Posts: 2661 Rating: (279)
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1/29/2009 10:58 PM	Rate (0)
Illum Posts: 4 Rating: (0)	Hi, I've found out to read the time of the cpu. But how do I compare with a time from an inputfield in the panel. Working with timeformats is quite new for me. So please give a hint about the format and how to compare them.
Illum Posts: 4 Rating: (0)
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1/29/2009 11:25 PM	Rate (0)
Phantom75 Posts: 2661 Rating: (279)	Illum . . . how do I compare with a time from an inputfield in the panel. . . . Hi Illum, You can declare a DT type variable on the panel and convert this to INT for comparison, but a better approach would be declare INT fields on the panel. One field each for hrs, min & sec. Then compare this with the corresponding bytes you read using SFC1. One thing important to note is, the values read by SFC1 are in BCD and you need to convert to INT (using instruction BTI) before comparing. Regards
Phantom75 Posts: 2661 Rating: (279)
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1/31/2009 8:19 PM	Rate (0)
Illum Posts: 4 Rating: (0)	Hi, Would you be able to give an eksample ? I'm looking for the TOD format and how to convert to INT. I already have a Areapointer "TIME_AND_DATE" (P#DB1.DBX16.0) from the PLC Clock, to compare with. I'm missing the TOD ( as a tag) from the panel, where I use a Date_and_time field with only the time. Hope not this is too confused. Regards Illum
Illum Posts: 4 Rating: (0)
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2/1/2009 3:41 PM	Rate (0)
Sydney Gold Member Joined: 1/4/2008 Last visit: 9/26/2024 Posts: 703 Rating: (96)	Hello Illum, you wrote about two different data types. DT (DATE_AND_TIME 8 bytes as Phantom75 mentioned for system time reading) and TOD (TIME_OF_DAY dword length). If you need just timecomparison I suggest to use TOD type which is easy to calculate and compare with as it's an unsigned integer number in milliseconds, with zero equal to midnight. You can use FC8 "DT_TOD" from the Standard library\IEC to convert DT to TOD andin the panel declare also TOD if it's possible, or INT fields as Phantom75 suggest, but then you have to recalculate them to TOD type. For the comparison then you can use directly STL instructions (DINT compare). Regards Sydney

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This contribution was helpful to 1 thankful Users Phantom75

2/2/2009 7:49 AM	Rate (0)
Illum Posts: 4 Rating: (0)	Hi everybody. I'vegot the point now. And my program works very fine. Thanks to everyone who show interest for my problem. Best resgards Illum
Illum Posts: 4 Rating: (0)
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