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How do you create a function in Siemens Step 7 which is equivalent to AOI in Rockwell say for example a function for Motor Starter. The function will be called multiple time for multiple motors. The function should have seperate memory for each devices. Using FB in conjunction with an associated DB is one way of doing it but for this we will have multiple functions (doing the same thing) for multiple devices. |
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You can group multiple FBs under one DB. Create an FB which will be you main routine. This FB when called will have a DB assigned to it. Create STAT variables in this FB for each instance of the blocks you wish to call. Under data type put the motors FB number. (You do this under the PLC registers sections and the top of the LAD editor. For example, suppose you create FB100 for your motors and you use FB1 for your main routine. Inside FB1 create STAT variables (let's call them Motor1, Motor2, etc.) of the type FB100. You can now call these blocks as if they had a separate DB, but all the memory will be grouped under the main DB used when FB1 is called. Let me know if this isn't clear and I can send you a screenshot. I think it's worth putting plenty of "spare" variables in the "STAT" area of FB100 so that your FB1 "STAT" area doesn't get messed up if you need to add new functionality to FB100.
(Apr 12 '10 at 09:38)
Allan Lewis
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