Introduction
This section describes the properties and technical specifications of the CPU if you operate it as a PROFIBUS DP master.
Reference
You can find the features and technical specifications of the 41x CPUs as of in this manual in Technical specifications.
Requirement
You will need to configure the relevant CPU interface for use as a DP master. This means that you do the following in STEP 7:
1. Configure the CPU as a DP master 2. Assign a PROFIBUS address.
3. Select an operating mode (S7-compatible or DPV1).
4. Assign a diagnostic address.
5. Connect DP slaves to the DP master system.
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PROFIBUS DP 5.1 CPU 41x as DP master / DP slave
Note
Is one of the PROFIBUS DP slaves a CPU 31x or CPU 41x?
If yes, you will find it in the PROFIBUS DP catalog as a "preconfigured station". Assign this DP slave CPU a slave diagnostic address in the DP master. Interconnect the DP master with the DP slave CPU, and define the address areas for data exchange with the DP slave CPU.
From EN 50170 to DPV1
The standard concerning distributed I/O (EN 50170) has been further developed. The results were incorporated into IEC 61158 / IEC 61784-1:2002 Ed1 CP 3/1. The SIMATIC
documentation refers to this as DPV1.
Operating modes for DPV1 components
• S7-compatible mode
In this mode, the components are compatible with EN 50170. Note that you cannot utilize the full DPV1 functionality in this mode.
• DPV1 mode
In this mode, you can utilize the full DPV1 functionality. Automation components in the station that do not support DPV1 can be used as before.
DPV1 and EN 50170 compatibility
You can continue to use all existing slaves after the system conversion to DPV1. These do not, however, support the enhanced function of DPV1.
DPV1 slaves can be used in systems that are not converted to DPV1. In this case, their behavior corresponds with that of conventional slaves. SIEMENS DPV1 slaves can be operated in S7-compatible mode. For the DPV1 slaves of other manufacturers, you need a GSD file < Rev. 3 file to EN 50170.
Further Information
Information on migratinbon from EN 50170 to DPV1 is available on the Internet, on the FAQ pages "Changing from EN 50170 to DPV1", FAQ ID 7027576, on the Customer Support website.
http://www.siemens.com/automation/service&support
Monitor/Modify, Programming via PROFIBUS
As an alternative to the MPI interface, you can use the PROFIBUS DP interface to program the CPU or execute the programming device functions Monitor and Modify.
Note
The execution of programming and monitor/modify functions via PROFIBUS DP interface
长沙工控帮教育科技有限公司整理
PROFIBUS DP
5.1 CPU 41x as DP master / DP slave
S7-400 Automation System, CPU Specifications
5-4 Manual, 11/2006, A5E00850746-02
Constant bus cycle time
This is a property of PROFIBUS DP that ensures same length bus cycles. The "Constant bus cycle time" function ensures that the DP master always starts the DP bus cycle within a constant interval. From the perspective of the slaves, this means that they receive their data from the master at constant time intervals.
The constant cycle time (isochrone) PROFIBUS is the basis for "isochrone mode".
Isochrone mode
S7-400 CPUs support the mechanism of isochronous reading and outputting of I/O signals.
This allows the user program to synchronize with the I/O processing. Input data is then recorded at a set time and output data takes effect at a set time.
Full "terminal-to-terminal" support of isochrone mode is only possible if all components within the sequence support the "isochrone mode" system property.
The "Isochrone Mode" manual contains a full overview of this system property.
Isochronous Updating of Process Image Partitions
SFC126 "SYNC_PI" is used to isochronously update a process input image partition. A user program which is linked to a DP cycle can use the SFC to update the input data in the process input image partition consistently and synchronously with these intervals. SFC126 accepts interrupt control and can only be called in OBs 61, 62, 63 and 64.
SFC 127 "SYNC_PO" is used to isochronously update the process output image partition. An application program which is linked to a DP cycle can use the SFC to transfer the computed output data from a process output image partition to the I/O consistently and synchronously with these intervals. SFC127 accepts interrupt control and can only be called in OBs 61, 62, 63 and 64.
To allow isochronous updates of process image partitions, all input or output addresses of a slave must be assigned to the same process image partition.
To ensure consistency of data in a process image partition, the following conditions must be satisfied on the various CPUs:
• CPU 412: Number of slaves + number of bytes / 100 < 16
• CPU 414: Number of slaves + number of bytes / 100 < 26
• CPU 416: Number of slaves + number of bytes / 100 < 40
• CPU 417: Number of slaves + number of bytes / 100 < 44
SFCs 126 and 127 are described in the corresponding Online Help and in the "System and Standard Functions" manual.
Consistent User Data
Data that belongs together in terms of its content and describes a process state at a specific point in time is known as consistent data. To maintain consistency, the data should not be changed or updated during processing or transmission.
You will find a detailed description of this procedure in the Consistent User Data section.
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PROFIBUS DP 5.1 CPU 41x as DP master / DP slave
Sync/Freeze
The SYNC control command is used to set sync mode on the DP slaves of selected groups.
In other words, the DP master transfers current output data and instructs the relevant DP slaves to freeze their outputs. The DP slaves writes the output data of the next output frames to an internal buffer; the state of the outputs remains unchanged.
Following each SYNC control command, the DP slaves of the selected groups transfer the output data stored in the internal buffer to the process outputs.
The outputs are only updated cyclically again after you transfer the UNSYNC control command using SFC11 "DPSYC_FR".
The FREEZE control command is used to set the relevant DP slaves to Freeze mode, in other words, the DP master instructs the DP slaves to freeze the current state of the inputs.
It then transfers the frozen data to the input area of the CPU.
Following each FREEZE control command, the DP slaves freeze the state of their inputs again.
The DP master receives the current state of the inputs cyclically, again not until you have sent the UNFREEZE control command with SFC11 "DPSYC_FR".
For information on SFC11, refer to the corresponding online help and to the System and Standard Functions manual
Startup of the DP Master System
Use the following parameters to set startup monitoring of the DP master:
• Transfer of the parameters to modules
• "Ready" message from the module
That is, the DP slaves must start up within the set time and be configured by the CPU (as DP master).
PROFIBUS Address of the DP Master
All PROFIBUS addresses are allowed.
长沙工控帮教育科技有限公司整理
PROFIBUS DP
5.1 CPU 41x as DP master / DP slave
S7-400 Automation System, CPU Specifications
5-6 Manual, 11/2006, A5E00850746-02