7/20/2017 9:07 PM | |
Posts: 241 Rating: (1) |
hi These pictures are print screen from s7 soft these are program of saw and cutting section of my company which produce chipboard, i have some questions about them 1-explain me about overall hw config 2-second question is that how i can analyse such heavy programs note that i am intermediate in automation and passed some fields about plc s7 300/400 programming and industrial networks the other sections programs are heavy such as this i mean they have several blocks and i am absolutely confused how and from which block i must start to analyse and finally i want to say cutting section has two saw which cuttings periodically and are servo motors thx AttachmentPictures.zip (105 Downloads) |
Last edited by: Jen_Moderator at: 7/21/2017 2:11:22 PMAdded Pictures as an Attachment. |
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7/20/2017 10:49 PM | |
Joined: 9/27/2006 Last visit: 9/4/2024 Posts: 12282 Rating: (2681)
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Hello hamed; Trying to understand another programmer's project can be difficult, whatever type of PLC in involved. Step 7 offers a few tools that might prove useful. But it does help if you already understand the process the program is controlling, and if the programmer was thoughtful enough to provide comments and symbolic names for the blocks and variables he is using. Step 7 works by cutting up different aspects of the process into manageable pieces (functions and function blocks) and organizes the memory allocation for the controls in specific DBs that contain the data for each block, if possible. Then. in the same manner that a program in C/C++ does, the main cyclic program (OB1) will call the basic functions one after the other to execute the full control alorith. For example, you mention that there are 2 saws in the process, each controlled by a servo motor. Having access to electric plans and lists will show you the I/Os used in the program for each of these, which will make your life easier later. Once you can locate the I/Os in the prject, I would start by looking at the Blocks folder and try to locate the calling FC/FB for the servo controls. If the 2 servos are te same (brand and model) then there should be 1 such block in the program, called at least 2 times (in 2 different blocks), one for each saw. There should be Datablocks (DBs) associated with the servo and saw functions also. You should study them and see what their structured data could teach you about the program. Now, about the tools I started discussing earlier. They are called Reference Data (cross-references), and they are very well described in the Programming with step 7 manual; here is a link to that document; SIMATIC Programming with STEP 7 - Siemens Let's say you have identified the servo and saw functions in the block folders; you know rthier name (FC122, for example) and their symbolic designation ("Servo drive", "Saw #1"...) if you open the Program Structure. you ill see the way that the blocks are called, wihich DB is accessed by the different blocks, so you will get an idea of how the program is run. Study the blocks which you have not identified, use the symbol table and the Cross-references to locate and identify the Inputs and outputs in each block call, coordinate with the electrical lists you accessed earlier... Slowly but surely you will get an idea of how the program has been built. But it takes patience and dedication... Hope this helps, Daniel Chartier |
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