3.11.1 Configuring and Commissioning the Diagnostic Repeater
This Diagnostic Repeater can monitor the segment of an RS485 PROFIBUS subnet (copper wire) during operation and report cable errors per diagnostics telegram to the DP Master. Via an HMI you can display the error location and the cause in plain-text.
The Diagnostic Repeater with its line diagnostic feature offers the possibility to recognizing and localizing line errors at an early stage and while in operation, thus reducing system standstill.
Configuring the Diagnostics Repeater
You can locate the Diagnostic Repeater in the hardware catalog under
"PROFIBUS DP\Network components\Diagnostic Repeater". The Diagnostic Repeater must be configured like any "Standard Slave" (it is connected to the master system of a DP Master).
Function of the Diagnostic Repeaters
To locate anomalies during operation, the Diagnostic Repeater must know the topology of the PROFIBUS subnet to which it is connected. The Diagnostic Repeater measures the distance to all partners via "Prepare line diagnostics "
function.
The Diagnostic Repeater measures the partner distances and stores them internally in a table. The Diagnostic Repeater also memorizes in which segment it has detected the partner.
After it has measured the distance to a segment error during operation, the table entries can be used to determine between which of the partners the segment fault is pending.
The Diagnostic Repeater interconnects 3 segments. During operation the
Diagnostic Repeater can determine the topology and localize segment errors only in Segments DP2 and DP3, because they are the only ones equipped with measuring lines. The figure below displays the Diagnostic Repeater (DR) and its connections.
Configuring the Distributed I/O (DP)
Prerequisites for Commissioning
The following prerequisites must apply:
• To be able to start capturing the topology, the PG must be connected to the PROFIBUS network.
• The structure of the PROFIBUS subnet with connected Diagnostic Repeater corresponds with the specifications and rules of the Diagnostic Repeater documentation.
Commissioning the Diagnostic Repeater with STEP 7
In order to be able to locate a disturbance during operation, the Diagnostic Repeater must know the topology of the PROFIBUS subnet to which it is connected. The Diagnostic Repeater measures the distance to all partners via
"Prepare line diagnostics " function.
The Diagnostic Repeater measures the partner distances and stores them internally in a table. The Diagnostic Repeater also memorizes in which segment it has detected the partner.
After it has measured the distance to an error during operation, the table entries can be used to determine between which of the partners the disturbance is pending.
You must explicitly instruct the Diagnostic Repeater to determine the distance between PROFIBUS partners when you configure your hardware or network:
1. Highlight the Diagnostic Repeater or the DP Master System to which it is connected (configure the hardware), or
highlight the PROFIBUS subnet to which the Diagnostic Repeater is connected (network configuration)
2. Select the menu command PLC > Prepare line diagnostics.
3. Start the measurement via the subsequently opened dialog.
Locating the Error During Operation
During operation the Diagnostic Repeater reports the event "Found Error" to the DP Master CPU.
You can view detailed information on pending diagnostic events in the dialog for the module status of the Diagnostic Repeater. The error is displayed visually in the dialog with additional information, for example, showing the error cause (provided it
Configuring the Distributed I/O (DP)
Example of Visual Presentation in the Dialog "Module Status"
If the functions of all segments to which the Diagnostic Repeater is connected are free of error, the corresponding tabs in the dialog "Module Status" are displayed as follows:
If a segment is switched off (that is, it is not possible to diagnose it), the following symbol will appear at the side of the register title:
Symbol for a switched off segment
An error in segment "DP2" results in an error symbol at the side of the "DP2" tab identifier. The remaining segments are free of error:
The "DP2" tab could show the disturbance in the following view: The Diagnostic Repeater is assigned to PROFIBUS address 4, the error is located between the partners assigned to the PROFIBUS addresses 16 and 21. In addition, the view shows the distance to the neighboring DP Slaves.
¨P
¨P ¨P
'3
In the figure below you can find an example of a simplified detailed presentation of the arrangement illustrated above.
3* 3*
Configuring the Distributed I/O (DP)
If STEP 7 does not localize the error in segment "DP2" or if, for example, this segment contains more than 32 partners and the Diagnostic Repeater cannot operate correctly anymore, you are shown the following image:
'3
Summary of all Symbols
The symbols o the registers can be of the following forms:
No segment error Segment error
Segment is switched off
Information cannot be retrieved from the segment
3.11.2 Displaying the Topology With the Help of Diagnostic Repeaters As of STEP 7 V5.2, in combination with a PROFIBUS configuration with Class 2 diagnostic repeaters 972-0AB01 it is not only possible to perform line diagnostics, but also to display the PROFIBUS DP network topology.
In contrast to the network view under NetPro, this function does not display the
"Logic" view of a PROFIBUS subnet, but rather the physical arrangement of the PROFIBUS nodes in their actual order as well as the distances to the nodes - provide the diagnostic repeater was able to determine these data. The actual nodes are displayed same as under NetPro.
Configuring the Distributed I/O (DP)
Function
Prior to displaying the topology, the "Prepare line diagnostics" function must be called initially after each modification of the hardware structure, in order to enable the diagnostic repeater to measure the PROFIBUS subnet and generate internal distance tables.
The "Display the PROFIBUS Network Topology" function is used to visualize these data.
If you select a subnet in a opened project and then display the topology, the nodes in the subnet are displayed along with their configured names.
In addition to the visualization, the entries in the diagnostics buffer of the diagnostic repeater as well as statistical data can be read and displayed.
You can write these data to a file and print it.
Requirements
The diagnostic repeaters must support the "Display the PROFIBUS Network Topology" function (i.e. as of order no. 6ES7 972-0AB01).
The structure of the PROFIBUS network must be in compliance with the guidelines in the diagnostic repeater manual, to be able to determine distances correctly.
Cascaded diagnostic repeaters, for example, may only be connected to a master diagnostic repeater via a DP1 interface.
To call the "Prepare line diagnostics" function, the PG must be connected directly to the same PROFIBUS as the diagnose repeater. The "Prepare line diagnostics"
function can also be called without open project.
To enable the "Display the PROFIBUS Network Topology" function, you can also connect the PROFIBUS network with its diagnostic repeaters via a "Data record router" (z. B. CP 443-5 Ext V3.2) to the PG. The PG must have been assigned in the STEP 7 project (Under NetPro, use menu command PLC > Assign PG/PC to configure the "PG/PC" object). To enable the display of a network topology via routed diagnostic repeater, you need to open the corresponding project and select the participating PROFIBUS subnet.
Procedure
Do one of the following:
1. In NetPro or in HW Config, select the menu command PLC > Prepare Line Diagnostics.