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Organisation block????

Created by: ilija28 at: 5/4/2009 12:27 PM (5 Replies)

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5/4/2009 12:27 PM	Rate (0)
ilija28 Posts: 5 Rating: (0)	Hi everybody. Can somebody tell me what meen "interrupt",when i use ,for example OB30. I use CPU312C with FC105 scale function to read analog values and store in DB. I think OB30 meen that the program will read from sensors every 5 seconds. Is this correct?????? How to increase that time,for example,30 sec?????
ilija28 Posts: 5 Rating: (0)
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5/4/2009 1:32 PM	Rate (0)
dchartier Grandmaster-Expert Joined: 9/27/2006 Last visit: 1/14/2026 Posts: 12481 Rating: (2722)	Hello ilija; Is there any reason you need to delay the reading and scaling of your analog inputs? Generally the FC105 block is simply called in OB1, there is very low overhead associated with it so readings are simply left to the main scan cycle. If youhave to use a cyclic interrupt block then you can modify the calling parameters of the OB3x you have in your CPU (I believe for the CPU 312C there is only OB35 available, with default setting at 100 ms) Simply overwrite this default valuein the CPU properties of the HWConfig editor, write in 30000 ms as the setting for 30 s call delay. Then you can call FC105 inside the OB35 block. Or use a free-running (self-resetting) pulse timer set to 30 s to call the FC105 conditionnally in OB1; this would work well too.. Hope this helps, Daniel Chartier

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5/4/2009 1:44 PM	Rate (0)
yy1 Posts: 535 Rating: (112)	Dear ilija28, the OB30 is used to get cyclic calls from the system (e.g. every 3s). As far as I know the OB30 is not supported by your CPU. You can change the execution-intervall in the 'Cyclic Interrupts'-tab of the CPU-properties (see attaced file). For more information about OBs and interrupts you can use the help-function, when the 'Cyclic Interrupts'-tab of the CPU-properties in HW-Config is opened. Regards, yy1 oops - too late Attachment 312C.JPG (235 Downloads)
yy1 Posts: 535 Rating: (112)	Last edited by: yy1 at: 5/4/2009 1:45 PM
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5/4/2009 2:16 PM	Rate (0)
ilija28 Posts: 5 Rating: (0)	I need to read analog values from the sensors at every 1 minute. This is a school project,not real,i just want to know how to set that !!!
ilija28 Posts: 5 Rating: (0)
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5/4/2009 8:12 PM	Rate (0)
ilija28 Posts: 5 Rating: (0)	dchartier Hello ilija; Is there any reason you need to delay the reading and scaling of your analog inputs? Generally the FC105 block is simply called in OB1, there is very low overhead associated with it so readings are simply left to the main scan cycle. If youhave to use a cyclic interrupt block then you can modify the calling parameters of the OB3x you have in your CPU (I believe for the CPU 312C there is only OB35 available, with default setting at 100 ms) Simply overwrite this default valuein the CPU properties of the HWConfig editor, write in 30000 ms as the setting for 30 s call delay. Then you can call FC105 inside the OB35 block. Or use a free-running (self-resetting) pulse timer set to 30 s to call the FC105 conditionnally in OB1; this would work well too.. Hope this helps, Daniel Chartier Becose,the analog to digital conversion needs about 176 ms,did i need to set that value in cyclic interrupt to be more than 176 ms?
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5/5/2009 7:24 AM	Rate (0)
dchartier Grandmaster-Expert Joined: 9/27/2006 Last visit: 1/14/2026 Posts: 12481 Rating: (2722)	ilija28 Becose,the analog to digital conversion needs about 176 ms,did i need to set that value in cyclic interrupt to be more than 176 ms? Hello Ilija; The only analog module of the S7-300 family that staes 176 ms conversion time is the 331-7KF02, and that is the value of the total module, all channels enabled, with a 12-bit resolution and a 50 Hz filter. For a single channel that value would be would be 22 ms. In any case, you have stated (on another forum) that you are using this for a school project, so here is my professional recommendation as you start off in automation: the basic principle in all automation projects should be the acronym KISS {keep it simple, st...]. It is not a derogatory term, just playful. It is meant to remind the designer of a project to focus on the important issues, and not lose time in re-inventing the wheel. Tools are provided, tested and documented, use them to build your program in the simplest and most productive way In your case, as stated before, I recommend you let the analog module handle the A/D conversion and transfer of data to the CPU,and if you only need to read the scaled value of the analog signal once a minute, call FC105 conditionnaly, after a timer has run for the allowed amount of time. Hope this helps, Daniel Chartier

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