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System Memory Bit's

Created by: girish bodhale at: 5/3/2014 7:09 AM (5 Replies)

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5/3/2014 7:09 AM	Rate (0)
girish bodhale Posts: 51 Rating: (1)	Hello, Am new to s7-300, but worked widely on s7-200, Recently we had a project on s7-300 platform, while working on it i discovered that there are no SM memory bits/bytes in it as it is in s7-200 So can any one help me where do i find these system memory bits. or is there any other way to do it. Please help
girish bodhale Posts: 51 Rating: (1)
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5/3/2014 10:53 AM	Rate (0)
Sachinpatke Silver Member Joined: 12/9/2010 Last visit: 10/8/2022 Posts: 623 Rating: (74)	Dear Girish, There are no special memory bits in S7-300. You will have to write logic on your own. Except clock byte. It is configured in HW config of CPU properties. All 8 bits have readymade sqaure wave of diffrent Hz.
	If you like the comment, rate it (right top) or thank it (left bottom). One who says he can & one who says he can't, are both correct-Confusius. Automation- C2C, Management Sachin Patke, India.
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5/3/2014 11:01 AM	Rate (1)
William_B Posts: 5225 Rating: (1175)	girish bodhale Hello, Am new to s7-300, but worked widely on s7-200, Recently we had a project on s7-300 platform, while working on it i discovered that there are no SM memory bits/bytes in it as it is in s7-200 So can any one help me where do i find these system memory bits. or is there any other way to do it. Please help Hi Friend, I very much loved working with the S7-200. Many of the functionality you may be looking for is built into the S7-300. It will be helpful if you tell us: (a) which functionality you are looking for (b) which PLC you using (c) what software you are using (Step7 5.x vs TIA V1x) (PS: I very much like your signature READ >> LEAD) From there I think we can introduce to you where to find the appropriate literature. --- I'll give you some pointers so long (I am assuming Step 7 5.x).. (a) Clock pulsing bits can be set in hardware configuration of the PLC. Some interrupts can also be seen there. These work through OBs. (b) OB100 is used to execute first run coding. (c) FirstScan / AlwaysOn / ScanPulse bits you will need to set up yourself. It is easier to do than you might think. (d) Look at the help description inside the program for math and shift functions. There are special mention about some system bits (example: carry bit). I am not going to spoil the discovery.. go have a look and follow through with some more digging. (e) The accumulators are not directly addressable. (S7-200: AC0.. AC3) --- As a final tip: STL is your friend.. far more easy to work with than on the S7-200. There are some things that are easier to achieve in STL than any other language. I hope thins helps a bit. Come back to us with more detail and I'm sure we'll provide more. Cheers. w
William_B Posts: 5225 Rating: (1175)	Last edited by: William B. at: 5/3/2014 11:02 AM Sorry.. missed the previous poster''''s notes.
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This contribution was helpful to 2 thankful Users rg-link felixboni

5/28/2014 8:21 AM	Rate (0)
SMHZ Bronze Member Joined: 10/19/2012 Last visit: 4/17/2022 Posts: 315 Rating: (9)	There are already many threads where u can get your answer: https://www.automation.siemens.com/tf/WW/en/Posts/21734

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5/29/2014 5:31 AM	Rate (0)
DS SURESH KUMAR Bronze Member Joined: 4/17/2012 Last visit: 9/7/2023 Posts: 474 Rating: (10)	/tf/WW/en/Posts/53043 check it

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6/2/2014 8:27 PM	Rate (0)
MHasan Posts: 63 Rating: (4)	You can check it by going on memory reference table.
MHasan Posts: 63 Rating: (4)
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