2 Configuring Central Racks
STEP 7 V5.3 Service Pack 1
4 Configuring PROFINET IO Devices
4.1 What You Should Know about PROFINET IO
4.1.1 What is PROFINET IO?
PROFINET is the Ethernet based automation standard of the German PROFIBUS User Organization [PROFIBUS Nutzerorganisation e.V. (PNO)] in Karlsruhe, Germany. It defines a communications, automation and engineering model that applies to all manufacturers.
Objectives
The objectives of PROFINET are:
• Consistent, uniform communication over field bus and Ethernet
• Open, distributed automation
• Use of open standards
Architecture
The PROFIBUS User Organization (PROFIBUS International) specifies the following characteristics for PROFINET architecture:
• Communication between controllers as components in distributed systems
• Communication between field devices such as peripheral (I/O) devices and drives
Implementation by Siemens
The requirement for "communication between controllers as components in
Configuring PROFINET IO Devices
4.1.2 PROFIBUS DP and PROFINET IO: Similarities and Differences
Compatibility and continuity – and, in doing so, protecting system investments – characterizes the further development of field technology from PROFIBUS DP to PROFINET IO.
The following section contains an introduction to the new concepts and terminology. It concludes with information on the similarities and differences between PROFIBUS DP and PROFINET IO.
For more detailed information, please refer to the brochure "From PROFIBUS DP to PROFINET IO".
Comparison of the designations used with PROFIBUS DP and PROFINET IO The following graphic shows the general designations of the most important devices used for PROFIBUS and PROFINET. The table after the graphic lists the names of the individual components used in PROFINET and PROFIBUS.
No. PROFINET PROFIBUS Comment
(1) IO system DP master system All IO devices (DP slaves) assigned to an IO controller (DP master)
(2) IO controller DP master Controller in which the user program runs
(3) IO supervisor (PG/PC) PG/PC Initial start up, HMI and diagnostics (4) Industrial Ethernet PROFIBUS Subnet type
(5) HMI HMI Device for operator control and
monitoring
(6) IO device DP slave Distributed field device assigned to a controller (i.e. remote IO, valve terminal, frequency converter)
Note: PG = "Programmiergerät" = "programming device"
Configuring PROFINET IO Devices
Similarities and differences
The following table contains key words and phases pertaining to the fundamental characteristics of field bus systems along with explanations of the similarities and differences between PROFIBUS DP and PROFINET IO from the standpoint of PROFINET IO.
Function Explanation
Real-time communication Deterministic, with update times determined by STEP 7 based on the hardware configuration.
With PROFINET IO, STEP 7 automatically determines the resulting update time, which can be manually increased, based on the hardware configuration.
Since PROFINET IO, in contrast to PROFIBUS DP, is based on another communication process, you do not need to deal with profiles and bus parameters.
Integration of field devices Done through installation of GSD files for both PROFIBUS DP and PROFINET IO.
With PROFINET IO, the GSD files are in XML format, but the files themselves are handled in the same manner as for PROFIBUS DP.
Configuration PROFINET IO is configured similarly to a DP master system. The only difference has to do with address assignment (due to Ethernet specifications).
For detailed information on address assignment, refer to the section in which this topic is discussed.
Slot model PROFINET IO is based on the slot model of PROFIBUS DP (DPV1):
PROFINET interface modules plug into slot "0" of the IO device; the modules or submodules with user data start with slot "1".
Download or download to programming device (PG)
No difference in configuration between PROFINET IO and PROFIBUS DP
Diagnosis Same diagnostic paths as for PROFIBUS DP (e.g. via station online, via accessible nodes) and options (i.e. module status).
Diagnostic extent similar to that for PROFIBUS DP (only the structure of the diagnostic data is somewhat different; only channel diagnosis is possible).
The structure of the diagnostic data records is, as with PROFIBUS DP, documented at the field devices (IO devices).
Blocks for the S7 user program and the system status lists (SSL)
Due to the larger data volumes for PROFINET IO, the system function blocks and the standard function blocks have to be adapted or re-implemented.
Similar to the situation for the blocks, the system status lists (SSL) were
Configuring PROFINET IO Devices
4.1.3 Assigning Addresses and Names for PROFINET IO Devices
IP addresses
All PROFINET devices use the TCP/IP protocol; for this reason, they need an IP address when operated on the Ethernet.
To simplify configuration, you will only be prompted once to assign an IP address:
when configuring the IO controller in HW Config.
At this point, STEP 7 displays a dialog for selecting the IP address and the Ethernet subnet. If the network is an isolated one, you can accept the default IP address and subnet mask assigned by STEP 7. If the network is part of an existing Ethernet company network, then you will have to ask you network administrator for this data.
The IP addresses of IO devices are generated by STEP 7 and normally assigned to the IO devices at the time the CPU is started up. The IP addresses of IO devices always have the same subnet mask as the IO controller and are assigned, starting from the IP address of the IO controller, in ascending order.
Device names
An IO device must have a device name before it can be addressed by an IO controller. PROFINET uses this method because names are easier to use and recall than complex IP addresses.
Assigning a device name for a specific IO device is comparable to setting the PROFIBUS address for a DP slave.
In their original, delivered condition, IO devices have no device names. IO devices can be addressed by an IO controller only after having been assigned a name by a programming device (PG)/PC, such as for transmitting configuration data (including the IP address ) at startup or for the exchanging user data in cyclical operation.
Devices on an Ethernet subnet must have unique names.
If an IO controller in another station is going to be operated at the same time as the IO device (e.g. CP 1616), then in the project the name assigned to this IO device must be the same as the name assigned to the IO controller on the hardware side.
This is the only case in which two nodes will have the same device names on the configured Ethernet subnet.
The device names must satisfy DNS conventions:
• Names are limited to a total of 127 characters (letters, numbers, dashes or dots)
• Any component part (that is, a character string between two dots) of the device name may only be up to 63 characters long.
• Names cannot contain any special characters such as umlauts, parentheses, underscores, forward or backward slashes, empty spaces, etc. The dash is the only special character allowed.
• Names must neither start nor end with the "-" sign.
Configuring PROFINET IO Devices
Structured device names
You can also structure the device name according to DNS conventions. To help you in structuring the names, use a period (".") as shown.
...<Subdomain Name>.<Domain Name>.<Top Level Domain Name>
STEP 7 supports you here by providing a prompt-driven dialog for using the name of the IO system in the device name:
<Name of specific device>.<Name of IO system>
You can set the name of the IO system at central location in the property dialog of the IO system.
When you copy an IO device to another IO system, STEP automatically applies the name of the IO system into which the device was inserted.
Device number
In addition to the device name, STEP 7 assigns a device number to the device when it is inserted. These numbers start with "1".
These device numbers are used to identify IO devices (e.g. SFC 71 "LOG_GEO") in the user program. Unlike the device name, the device number is not visible in the user program.
Configuring PROFINET IO Devices
4.1.4 Integrating Existing PROFIBUS DP Configurations
Connecting PROFINET and PROFIBUS
PROFIBUS devices can be connected to the local PROFIBUS interface for a PROFINET device. In this way, you can integrate already existing PROFIBUS configurations into PROFINET.
The following illustration shows the network types supported for PROFINET:
Industrial Ethernet and PROFIBUS.
No. Description (1) PROFINET device
(2) PROFINET device with proxy functionality (e.g. IE/PB link) (3) PROFIBUS devices
Configuring PROFINET IO Devices
PROFINET devices with proxy functionality = Generic
The PROFINET device with proxy functionality is the substitute equivalent of a PROFIBUS device on the Ethernet. The proxy functionality allows a PROFIBUS device to communicate not only with its master but also with all nodes on PROFINET.
With this proxy functionality, there are no problems in integrating existing PROFIBUS systems into PROFINET communication.
For example, if you connect a PROFIBUS device to PROFINET by means of an IE/PB link, the IE/PB link establishes the communication via PROFINET as a substitute for the PROFIBUS-components.
Configuring PROFINET IO Devices
4.1.5 Update Times For Cyclical Data Exchange
Because of the fully different kind of communication process used with
PROFINET IO, you do not have deal with a series of bus parameters, unlike with PROFIBUS DP.
However, just like with PROFIBUS DP, STEP 7 automatically determines a time period within which a PROFINET IO device has exchanged its user data with the associated IO controller: this is known as the "update time".
Based on the hardware configuration in use and the resulting amount of cyclical data, STEP 7 automatically calculates update times, which you can increase manually if necessary. You can set equal update times for all IO devices in the PROFINET IO system or set individual times for each IO device.
If you consider a single IO device in the PROFINET IO system, the IO controller provides this IO device with new data (outputs) within this update time, and the IO device has sent its latest data (inputs) to the IO controller within this time.
Properties of the update time
The update times can only be set in certain fixed intervals (time bases). The values that are considered are determined by STEP 7 from the properties (that is, from the GSD files) of the IO devices concerned.
If you change the hardware configuration, such as by adding new IO devices, the update time may have been changed. If so, the next time you open the dialog, a message will inform you that a change has been made.
What factors influence the update time?
• The number of IO devices
• The number of inputs and outputs
• The percentage of time reserved for PROFINET IO
• The properties (performance) of the IO controller
• The IRT time (if isochronous realtime communication was configured)
Configuring PROFINET IO Devices
Reading and setting the update time globally from a central location
To open the dialog to read and change the update time, proceed as follows:
1. Double-click the IO system (the "railroad track").
2. Select the "Update Time" tab.
- If, in addition to PROFINET IO, other cyclical services (i.e. from
Component-based Automation, CBA) have to be taken into consideration:
Go to the "Communication Component (PROFINET IO)" field and select a percentage that should be reserved for PROFINET IO.
If at least one IO device is configured, then the default setting is 100%.
If no IO device is configured, then the default setting is 0%.
- Select the desired option for setting the update time: for the entire IO system or for a specific device.
3. If you like, you can increase the update time (for the entire IO system or for a specific IO device).
Tip
Regardless of the option that you select: the dialog always shows the calculated or already configured update times. This applies to a setting for the entire IO system or a setting for a specific IO device.
Reading and setting the update time at the IO device
To open the dialog to read and change the update time for specific IO device, proceed as follows:
1. Double-click the IO device.
2. Select the "IO Cycle" tab.
3. Check the current setting for the update time. If necessary, change it and then confirm the settings with "OK".
Configuring PROFINET IO Devices
4.1.6 Setting a Specific Update Time for an IO-Device
With STEP 7 V5.3, Service Pack 1, you can set an update time that applies to all IO devices in a PROFINET IO system. In this case, the slowest IO device will determine the update time, even if shorter update times would be possible for individual IO devices.
As of STEP 7 V5.3, Service Pack 2, you have the option of setting separate update times for individual IO devices. This option is called "Set a specific update time for an IO device". The option of setting a uniform update time for all IO devices is still available. This option is called "Set update time for all IO systems".
Procedure
1. Double-click the IO system (the "railroad track").
2. Select the "Update Time" tab.
- If, in addition to PROFINET IO, other cyclical services (i.e. from
Component-based Automation, CBA) have to be taken into consideration:
Go to the "Communication Component (PROFINET IO)" field and select a percentage that should be reserved for PROFINET IO.
If at least one IO device is configured, then the default setting is 100%.
If no IO device is configured, then the default setting is 0%.
- Select the "Set a specific update time for an IO device" (if it is not already selected by default).
- The IO devices are listed in the field below. STEP 7 has already calculated an optimal update time for each IO device.
The update times for IO devices that do not exchange user data (e.g. a switch) are identified with an asterisk (*). As a rule, the update times for these PROFINET devices are higher than those for the remaining IO devices.
- If necessary, sort the information displayed in a column by clicking the column header. To display the information in the opposite sequence, click the column header again
- To change the update time, double-click the row with the desired device number.
Tip
To set the update time at once for several IO devices, select the IO devices concerned (multiple selection) and click the "Edit" button". To select multiple devices, you can select each one in sequence while holding the CTRL key down.
Optimizing the update times for individual IO devices
Based on the configuration, STEP 7 calculates the optimized (the shortest possible) update times. However, by increasing the update times for individual IO devices that supply data that do not have to be absolutely available at a definite time (not time-critical), you can expand the leeway available in order to allow shorter update times for other IO devices.
Configuring PROFINET IO Devices