show the entry list
PROFIBUS general -- Configuring and programming communication -- Using communication blocks
Transfer of analog values from and to the PROFIBUS DP slave
Which entries deal with consistent data in conjunction with distributed I/O?
How can you access consistent data without SFC14/15 as part of the process image?
Why does my new CPU 315-2DP (Order No: 6ES7 315-2AG10-0AB0) not process the SFC13 correctly?
How do you receive an alarm with the SFB 54 "RALRM" in compliance with DPV1?
DP slave lifelist using SFC51 "RDSYSST" instead of SFC12 "D_ACT_DP"
Can you use the "Signal System Error" function, the FB126 function block and the SFC13 "DPNRM_DG" system function simultaneously?
Notes for the use of the system function SFC12 "D_ACT_DP"
What is consistent data?
How do you read data consistently from a DP standard slave/PROFINET IO device and write it consistently to a DP standard slave/PROFINET IO device?
Disabling DP slaves after startup of the CPU
Diagnostics information of the FB125 with disabled DP slave
Enabling a disabled DP slave with SFC 12 "D_ACT_DP"
Parameter assignment of SFC 103 / SFC 59 required for identifying and reading out topology data
What are the requirements for using the "Prepare Line Diagnostics" function?
S7-300 CPU 31x -- Configuring and programming communication -- Configuring the PROFIBUS interface
How do you activate the "Prioritized OCM communication" function to improve the OP communication performance?
How do you configure a connection between WinCC flexible Runtime (PC/Panel) and a SIMATIC S7-300/S7400 via PROFIBUS/MPI?
What differences are there when configuring S7 connections?
Transfer of analog values from and to the PROFIBUS DP slave
What should you pay attention to when operating a DP slave temporarily on a PROFIBUS DP network?
How do you configure an S7 connection via MPI with the SIMATIC NET OPC server and the SIMATIC NET PC software?
How do you configure a PC station as DP slave for connecting an S7 station (as DP master) for the SIMATIC NET OPC server with the SIMATIC NET PC software?
What are the differences between the integrated DP interface of a CPU (e.g. CPU 315-2 DP) and the DP interface of the CP 342-5?
How do you read data consistently from a DP standard slave/PROFINET IO device and write it consistently to a DP standard slave/PROFINET IO device?
What are the options for exchanging data between CPUs via MPI/PROFIBUS DP?
Direct data exchange (internode communication) between two CPU modules
S7 routing via PROFIBUS with S7-300
Rules for accessing the CPU 315-2 DP on distributed I/O (integrated DP interface of CPU 315-2 DP)
Startup of the S7-300 CPUs when slave is not available
Routing with compact CPU and C7-635 as DP slave
How can you tell whether your S7-300/400 master supports DPV1 functions?
S7-400 CPU 41x -- Configuring and programming communication -- Configuring the PROFIBUS interface
How do you configure a connection between WinCC flexible Runtime (PC/Panel) and a SIMATIC S7-300/S7400 via PROFIBUS/MPI?
What do you have to consider when connecting a S7-400 CPU to an external master as DP slave?
What differences are there when configuring S7 connections?
Transfer of analog values from and to the PROFIBUS DP slave
What should you pay attention to when operating a DP slave temporarily on a PROFIBUS DP network?
How do you configure an S7 connection via MPI with the SIMATIC NET OPC server and the SIMATIC NET PC software?
How do you configure a PC station as DP slave for connecting an S7 station (as DP master) for the SIMATIC NET OPC server with the SIMATIC NET PC software?
How do you read data consistently from a DP standard slave/PROFINET IO device and write it consistently to a DP standard slave/PROFINET IO device?
How can you tell whether your S7-300/400 master supports DPV1 functions?
Where are the settings of the MPI and PROFIBUS interfaces retained after updating the operating system for a CPU 41x?
S7-300 CPU 31x -- Configuring and programming communication -- Configuring PROFINETinterfaces
In the user program, how do you read out the Link State of the PROFINET interface of a S7-300 CPU?
Which settings do you have to make in the TIA Portal to read out messages and status information over the CPU's web server and display them in the web browser?
How do you display the diagnostics buffer of a SIMATIC CPU with integrated web server on a SIMATIC Panel?
Which "local_device_id" do you parameterize in order to establish a connection to FB65 "TCON" for open communication via Industrial Ethernet?
How do you reset the IP address and device name of an I device?
Why is the message "This page is not available" displayed in the web browser when you call the HTML page "Topology", for example, to read out the topology via the web server of the CPU?
How do you activate the "Prioritized OCM communication" function to improve the OP communication performance?
What should you watch out for when parameterizing the watchdog time when a ring redundancy is established with the Media Redundancy Protocol?
Which CPU can you operate as a PROFINET I device?
What should you watch out for with a remote access to a SIMATIC S7 with STEP 7 via the Internet?
In the user program of an S7-300 or S7-400 CPU with integrated PN interface, how can you read out the current topology of the PROFINET IO system connected?
Where can you find sample S7 programs and documentation for communication via PROFINET on the SIMATIC NET Quick Start Collection?
What differences are there when configuring S7 connections?
Which settings are required to access the web server of the CPU via a PC with a second network card even though a proxy server is set?
Can you implement an S7 317-2 PN/DP CPU instead of an S7 315-2 PN/DP CPU configured in iMap?
How do you read data consistently from a DP standard slave/PROFINET IO device and write it consistently to a DP standard slave/PROFINET IO device?
What can you do when communication errors occur sporadically with a PROFINET interface of the S7 300 CPU 31x-2 PN/DP?
From which library should you take the communications FBs?
What are the commonalities and differences between configured communication connections and the open Ethernet communication?
What are the differences when assigning the MAC address?
S7-400 CPU 41x -- Configuring and programming communication -- Configuring the PROFINET interface
Which settings do you have to make in the TIA Portal to read out messages and status information over the CPU's web server and display them in the web browser?
Why is the "Certificate error" message shown in the address line when downloading the web page of an S7-300/400/1200 CPU over "https://..."?
How do you display the diagnostics buffer of a SIMATIC CPU with integrated web server on a SIMATIC Panel?
Which "local_device_id" do you parameterize in order to establish a connection to FB65 "TCON" for open communication via Industrial Ethernet?
Why is the message "This page is not available" displayed in the web browser when you call the HTML page "Topology", for example, to read out the topology via the web server of the CPU?
How do you reset the IP address and device name of an I device?
What should you watch out for when parameterizing the watchdog time when a ring redundancy is established with the Media Redundancy Protocol?
Which CPU can you operate as a PROFINET I device?
What should you watch out for with a remote access to a SIMATIC S7 with STEP 7 via the Internet?
In the user program of an S7-300 or S7-400 CPU with integrated PN interface, how can you read out the current topology of the PROFINET IO system connected?
Where can you find sample S7 programs and documentation for communication via PROFINET on the SIMATIC NET Quick Start Collection?
Which settings are required to access the web server of the CPU via a PC with a second network card even though a proxy server is set?
What differences are there when configuring S7 connections?
How do you read data consistently from a DP standard slave/PROFINET IO device and write it consistently to a DP standard slave/PROFINET IO device?
How do you read data consistently from a DP standard slave/PROFINET IO device and write it consistently to a DP standard slave/PROFINET IO device?
Part number:

Description

SFC14 "DPRD_DAT"
Using the system function SFC 14 "DPRD_DAT" (read consistent data of a DP standard slave) you read out the data of a DP standard slave/PROFINET IO device. If no errors occurred during the data transfer, the data read is entered into the target area set up by RECORD. The target area must have the same length as you configured with STEP 7 for the selected module. With a DP standard slave with modular structure and with multiple DP identifications, with an SFC 14 call you can only ever access the data of one module / DP identification under the start address configured.

SFC15 "DPWR_DAT"
Using the system function SFC 15 "DPWR_DAT" (write consistent data to a DP standard slave) you transfer the data in RECORD consistently to the addressed DP standard slave/PROFINET IO device. The source area must have the same length as you configured with STEP 7 for the selected module.
With a DP standard slave with modular structure you can only access one module of the DP slave.

Maximum length and addressing of consistent user data areas on the PROFIBUS DP
In the manuals listed below you will find more information about the maximum length and addressing of consistent user data areas on the PROFIBUS DP.
 
Manual Chapter / Section Entry ID
SIMATIC S7-300 CPU 31xC and CPU 31x: Configure Addressing 13008499
SIMATIC Distributed IO ET 200S Interface Module IM151-7 CPU Addressing 56046285
SIMATIC Distributed IO ET 200S Interface Module IM151-8 PN/DP CPU Addressing 47409312
SIMATIC ET 200pro Interface Module IM 154-8 PN/DP CPU Addressing 44251850
SIMATIC Basic Module BM 147/CPU Addressing 1142364
Automation System SIMATIC S7-400 CPU Specifications Consistent Data 53385241
Table 01

Maximum length and addressing of consistent user data areas on the PROFIBUS IO
In the manuals listed below you will find more information about the maximum length and addressing of consistent user data areas on the PROFIBUS IO.
 
Manual Chapter / Section Entry ID
SIMATIC S7-300 CPU 31xC and CPU 31x: Configure Addressing 13008499
SIMATIC Distributed IO ET 200S Interface Module IM151-8 PN/DP CPU Addressing 47409312
SIMATIC ET 200pro Interface Module IM 154-8 PN/DP CPU Addressing 44251850
Automation System SIMATIC S7-400 CPU Specifications Consistent Data 53385241
Table 02

For communication processors (CPs) the size of the consistent area for a submodule is defined as follows.
 
CP MLFB Upper limit
CP 443-1 6GK7443-1EX20-0XE0 240 bytes
CP 443-1 6GK7443-1EX30-0XE0 240 bytes
CP 443-1 Advanced 6GK7443-1EX40-0XE0 128 bytes
CP 443-1 Advanced 6GK7443-1EX41-0XE0 240 bytes
CP 443-1 Advanced 6GK7443-1GX20-0XE0 240 bytes
CP 443-1 Advanced 6GK7443-1GX30-0XE0 240 bytes
CP 343-1 6GK7343-1EX21-0XE0 128 bytes
CP 343-1 6GK7343-1EX30-0XE0 240 bytes
CP 343-1 Advanced 6GK7343-1GX21-0XE0 128 bytes
CP 343-1 Advanced 6GK7343-1GX30-0XE0 240 bytes
CP 343-1 Advanced 6GK7343-1GX31-0XE0 240 bytes
Table 03

Notes
The PROFIBUS DP standard defines upper limits for the transfer of consistent user data. Current DP standard slaves keep to these upper limits. Older CPUs (<1999) have CPU-specific restrictions for the transfer of consistent user data.
The maximum length of data that these CPUs can read consistently from a DP standard slave or write consistently to a DP standard slave is given in the technical data under "DP master – user data per DP slave". With the value, more recent CPUs exceed the length of the data that a DP standard slave provides or receives.

Important
Distributed reading and writing of consistent data (<4 bytes) is also possible without system functions SFC14 and SFC15. Which modules you can use for this is described in Entry ID 8751062.

The table below shows the access to consistent data outside the process image.
 
Length of data area Read/write access Consistency of data
1 byte Load / Transfer Consistency over unit
2 bytes Word Load / Word Transfer Consistency over total length
3 bytes SFC14 / SFC15 Consistency over total length
4 bytes Double-word Load / Double-word Transfer Consistency over total length
5 bytes SFC14 / SFC15 Consistency over total length
Table 04

Example
In the example below an S7-400 CPU is used as DP master and a CP342-5 as DP slave.

The consistency area below is defined for the inputs and outputs of the DP slave:

  • For the outputs, 50 bytes are transferred consistently over the total length. These 50 bytes are available consistently in the process image partition 3 (PIP 3) of the S7-400 CPU and can therefore be read using load/transfer commands.
  • For the inputs, 20 bytes are transferred consistently over the total length. These 20 bytes are not stored in the process image or in process image partition and can only be written with the system function SFC14/15.


Fig. 01

The operating system of the CPU transfers the data consistently during process image updating. You can access this data in the process image using the load and transfer commands.
Alternatively, with S7-400 CPUs you can use system function SFC 26 "UPDAT_PI" or SFC 27 "UPDAT_PO" at any point in the program to update the process images. However, in this case the relevant PIP may not be updated by the system. If you do not or cannot place the data in a process image, then you should use the system functions SFC14 and SFC15 for data communications.

More information about this is available in the following entries:

  • "Consistent data in S7-400, summary of mechanisms" - Entry ID: 11646774
  • "Use of Process Image Partitions in Organization Blocks" - Entry ID:18325216

 Entry ID:21848242   Date:2012-12-20 
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