6/29/2020 1:18 PM | |
Joined: 5/12/2006 Last visit: 9/25/2024 Posts: 22371 Rating: (3014) |
Hello, capter 7 https://support.industry.siemens.com/cs/ww/en/view/44240604 LADDR = IO Adress in hex (100h = 256dec) RECNUM = Dataset number which used in hex (2fh = 47Dec) IOID =54 because you use Peripherial to access the data in you code you read/write dataset 47 with the device which have Inputadress 256. regards christoph |
Last edited by: ChristophD at: 06/29/2020 13:19:54 |
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6/30/2020 4:12 PM | |
Joined: 9/27/2006 Last visit: 9/25/2024 Posts: 12283 Rating: (2685)
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Hello Alex; The use of SFC 14/15 and SFC 58/59 is not related. The first is for reading and writing constent data to a Profibus slave (or Profinet IO device), the other pair of functions is used to read data records as you have experienced already. The words "consistent data" seem to create misunderstandings for programmers. Whenever you create an exchange table with devices on Profibus or Profinet, yoiu can set the data consitency "by unit" or "by total". A word, or a Dword is a consistent amount data, per unit. 12 words can be read as consistent data per unit, but then your program must access them word by word. If you want to read/write them as a single unit (like a telegram would) you need to access them "by total", using SFC 14/15. In most cases it is only a question of personal taste r programming habits by the user; both methods transfer the data to the PG and the PLC in the same amount of time and in about the same way. But there re instances when it is required to use SFC 14/15 to ensure the data is consistent. One example is the drive's PKW mechanism: to read or write a single parameter of the drive through Profibus/Profinet, you must use SFC 14/15 to send a total of 4 words consistent by total (this is mandated by the Profidrive profile). If you try to write 4 distinct words, the drive will reject them. It can only handle parameter information as a block (or telegram) of 4 words. Have a look at the following FAQ, it discusses the PKW mechanism for Siemens drives (using Profidrive). It also gives you access to examples projects that show: - 2 different ways of read/writing PZD (process data) to a Siemens drive, using either L/T (Move) instructions (using consistency by unit) or telegrams (using SFC 14/15); - 2 different projects showing how SFC 14/15 must be used to read or write to the drive's parameters. https://support.industry.siemens.com/cs/ww/en/view/8894584 Hope this helps, Daniel Chartier Edit: if the CP 340 you are asking about does not show a connection on the project electrical plans, does it actually have a connection to some physical module somewhere? Since it is a RS 232 model, the CP 340 can only be connected to one slave at a max distance of 15 m, so follow the wire, if there is one. If you locate that slave, tell us what it is (module make and model), maybe we can help you find out more about how the communication is programmed in your program. D.C. |
Last edited by: dchartier at: 06/30/2020 16:17:21 |
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