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what is the meaning of Data Consistency

12/29/2016 11:46 PM	Rate (0)
neklawy 88 Experienced Member Joined: 8/18/2016 Last visit: 12/23/2025 Posts: 115 Rating: (0)	hi every body i am beginner in plc and i want know what is the meaning of Data Consistency and i read the help in simatic but i cant understand it can any on help me and explain it in simple way

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12/30/2016 9:26 AM	Rate (1)
Sachinpatke Posts: 623 Rating: (77)	Hi, Data consistency of project is attained by 'compile all' function of simatic manager. Majorly it checks FB and its instances are updated to identical version. If data consistency of prj is not intact, CPU may go to fault or misbehave.
Sachinpatke Posts: 623 Rating: (77)
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This contribution was helpful to 2 thankful Users Sandeep Bakoliya OMKRIS2017

12/30/2016 10:50 AM	Rate (1)
mopS04 Posts: 5521 Rating: (1058)	hi abdalla, I think Wikipedia entry describes it very good: Wikipedia Data Consistency refers to the usability of data; we want data to be constant in time and for us to be capable of using and showing them in different ways without changing their structure. Have a look to the whole entry. Data consistency hope this helps, regards,
mopS04 Posts: 5521 Rating: (1058)
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This contribution was helpful to 1 thankful Users OMKRIS2017

1/4/2017 9:40 AM	Rate (0)
brian.grimshaw Posts: 61 Rating: (11)	I always think of it in simple terms: Imagine that we have a word (2 bytes) and we are incrementing the word At the same time, some routine is copying this data somewhere else e.g. to a comms card We will have a situation where both bytes change at the same time, like counting from 255 to 256 (00000000 11111111 to 00000001 00000000) If the copy can happen at any time, we could have read the low byte then increment then read the high byte. The copy will read 255 + 256 = 511 (00000001 11111111). This is inconsistent data. To ensure data consistency, we could delay the copy while the increment is executing, or the other way round. Hope that helps, Brian
brian.grimshaw Posts: 61 Rating: (11)
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This contribution was helpful to 2 thankful Users neklawy 88 OMKRIS2017

8/3/2021 9:13 PM	Rate (0)
OMKRIS2017 Bronze Member Joined: 1/1/2017 Last visit: 10/30/2025 Posts: 343 Rating: (11)	Thanks a Lot guys!

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