9/7/2022 6:44 AM | |||
Joined: 10/19/2020 Last visit: 8/21/2024 Posts: 4 Rating:
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Kind users, i'm here to ask about the use of DPRD_DAT, more specifically, when should it be used. i've read both the manual and this wonderful article here : https://support.industry.siemens.com/cs/mdm/109759862?c=86660468363&lc=nl-NL A doubt still remains in my mind. Basically, the article says that i should use this instruction to get data from a Profinet I/O device, while i don't need to use it to get data from Protinet devices. I guess it is a *** thing but... ultimately the question is...what is the difference between profinet I/O device and profinet device? i should consider profinet I/O device every device from which i read i/o? or else? Also, the article says also this:
i don't understand this (yes i referred to the article mentioned). Shouldn't the use of dprd_dat itself make the data consistent, and therefore the removal should be done every time i use this instruction? or there is a specific definition to a "consistent data" that make it such and i MUST read it with dprd_dat? sorry for the confusion and thanks to anybody willing to help. (in case it wasn't clear, english is not my mother language, sorry for any mistake). |
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Last edited by: ploppolissimo at: 09/07/2022 08:54:16 |
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9/7/2022 9:15 AM | |
Joined: 1/21/2013 Last visit: 9/5/2024 Posts: 3084 Rating:
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Hi ploppolissimo. in chapter 'DPRD_DAT and DPWR_DAT (Read/write consistent data)' of the system manual 'S7-1200 Programmable controller' you can find the following: PROFINET supports up to 1024 bytes of consistent data. You do not need to use these instructions for consistent transfers between the S7-1200 and PROFINET devices. For the S7-1500 you can find the following in chapter 'Process image - overview' of the system manual 'S7-1500, ET 200MP Automation system': When the process image is updated, the S7-1500 accesses the data of each submodule as consistent data. The maximum data width that is accessed as consistent data for each submodule is dependent on the IO system. For PROFINET IO, for example, this data width is 1024 bytes. For moving peripheral inputs into a data block, I use PLC data types for my PLC tags and inside the data block. Thus a simple MOVE statement or in SCL an assignment is sufficient. Kind regards |
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2 thankful Users |
9/7/2022 1:04 PM | |||
Joined: 7/7/2010 Last visit: 9/4/2024 Posts: 15139 Rating:
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The article is telling you either use telegrams to handle PN I/O, or use DPRD_DAT. Either solution will provide consistent data for PN devices. However, telegrams require no code that needs to be written, maintained, explained, monitored, documented in order to populate I/O tags assigned to the telegram I/O addresses.
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science guy |
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9/8/2022 6:35 AM | |||
Joined: 10/19/2020 Last visit: 8/21/2024 Posts: 4 Rating:
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Thanks for your kind answer. Honestly i don't think i get what you mean with using "telegrams", since the article doesn't state that word. You mean that telegrams are used to delivery those input i configure in the HW config. into the PLC i/o ? where did you read this?
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Last edited by: ploppolissimo at: 09/08/2022 09:23:42 |
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