QUESTION:
What should you watch out for when setting up the Redundancy option?

ANSWER:
Below are a number of notes on general configuration. 

Please note that the points listed here are merely in addition to the user manual Redundancy.

Basic parameterization (WinCC V5.1)

1. The requirement for Redundancy is time synchronization between both redundant servers. This is necessary to make sure that entries are not duplicated in the message system, for example. Likewise, this also avoids any faulty displays of curves in Trend Controls.
   
   In WinCC you can use the Smart Tool 'DCF77' provided for time synchronization. It is located on the WinCC CD-ROM. More information on time synchronization with DCF77 is also available on the WinCC CD-ROM in the following directories:   
   
     \SmartTools\DCF77Client\Dcf113Client.htm (WinCC V4) 
     \SmartTools\DCF77Client\dcf77index.htm     (WinCC V5), see also Entry ID 622814.
   
   DCF77_Client ( 7 KB )    
2. The project is first created on SERVER1. The configuration mask for Redundancy is filled in accordingly. 
   
   Important: you must enable the option field 'Activate Redundancy'.
   
   Redundancy configuration mask ( 9 KB )    
3. You make the following changes through the 'Redundancy' configuration mask: the configuration data is stored in a file:
   
       Project directory\Redundancy\Data.CS         (binary file)
       Project directory\Redundancy\Data.CS.txt    (ASCII format for checking)
   
   Important: CCRedCodi.exe is entered in the Startup list of the computer.
4. Import WinCC system messages. These have to be created manually in the Alarm Logging Editor under "TOOLS >WinCC System messages...".
   
   WinCC system messages ( 6 KB )  
   
   A description of the WinCC system messages is available in the WinCC Online Help under the search term 'System messages from Redundancy'.
5. Using the WinCC Project Duplicator copy the project to SERVER2. The call is via 'Start > SIMATIC > WinCC > Project Duplicator'. Specify the source project and the path to SERVER2, then click 'Duplicate'.
   
   Important: WinCC must be closed on SERVER1
   
   WinCC Project Duplicator ( 5 KB )  
6. To check whether duplication was successful, open the project on both servers. Then start Runtime on SERVER1. With the Task Manager of Windows NT a check is made as to whether CCRedCodi.exe has been started on SERVER1. Then the same is checked for SERVER2 (here Runtime still hasn’t been started). CCRedCodi.exe has to have been started via the network of SERVER1.
7. If you now start Runtime on SERVER 2, the system messages from the start of the alignment are displayed in the WinCC Alarm Logging Archive.
   
   Important: please make sure that there are about 3 minutes between the two Runtime starts (monitoring time).

Diagnostics options

1. If CCRedCodi.exe has not yet been started on SERVER2, you need to check the connection with DCOM Test. See here also the description in the WinCC Information System under the search term 'DCOM'.
2. If the alignment doesn’t work, proceed as follows: 

• Delete the file  'Data.RT' in the WinCC Project Directory\Redundancy on both servers.
  Note: WinCC must be closed and CCRedCodi.exe must not be running on either of the servers. 
• Then start both computers at the same time. No failures should be signaled.
• Close Runtime on SERVER1. This should be signaled as a failure on SERVER2.
• Then trigger a number of messages on SERVER2 and also archive curve values.
• After a while start Runtime again on SERVER1. This should also be signaled on SERVER2. 
• The beginning and end of the alignment is also signaled there. At the end of the alignment you should check whether messages triggered during the failure period are also displayed in the archive of SERVER1. The gaps in the curves should also be filled in.

3. General information on failures and alignment is available in the following file:
   c:\siemens\wincc\diagnose\CCRedCodi.log

Alignment of the archives
The individual failure criteria for alignment are described in the WinCC Options Manual, section 3.6 'Failure Scenarios'. For online alignment of User Archives there are useful descriptions in the Online Help of WinCC under the item 'Redundant User Archives'.

Check list: Switching clients
This option is to switch a WinCC client – that is connected to SERVER1 for example – to the redundant server – e.g. SERVER2 – if its server fails. Switching means that the old project is closed and a new project is opened on the other server (SERVER2).

1. Note:  
   The Redundancy options package has to be installed on the redundant servers and on the client. 
2. Open the local projects on both servers. Then start the Project Switcher program on the clients via the Windows Start menu fill in the mask accordingly. Enter the complete paths with both server projects:
   
   Example:        
   
   WinCC Project Switcher ( 6 KB )  
3. The order of standard project and partner project is irrelevant. You must also enable "Activate project switcher" with a check mark:

• On the clients the file CCProjectSwitcher.dat is created in the path c:\siemens\wincc\bin. This has the ASCII format and can therefore be checked with the Notepad editor.
• In the opened project the following program is attached to the Startup list for the client: ...\siemens\wincc\bin\CCProjectSwitcherRT.exe

4. Test: switch in case of failure
   The failure case can be tested, for example, by interrupting the network connection between WinCC server SERVER1 and WinCC client. In this case the client should switch to SERVER2. 
5. Test: manual switching
   The switch procedure can also be triggered manually by writing the @RM_SWITCHER variable with the name of the client to be switched. In this case a switch is made to another server.

Descriptions and notes on the WinCC Project Switcher are available in the WinCC Online Help under the items 'WinCC Redundancy Project Switcher' and 'Function of the Redundancy Option'.

Internal variables
In WinCC, the following internal variables are created automatically when Redundancy is set up:

• @RM_MASTER 
• @RM_MASTER_NAME
• @RM_SERVER_NAME
• @RM_UA_ONL_"Archivename" 
• @RM_OFFLINE_UA_NAME

A description and explanation of these system variables is available in the WinCC Online Help under the item 'System Variables of WinCC Redundancy'.

These variables can be displayed in a WinCC picture and used for diagnostics and monitoring. For example, with the @RM_SERVER_NAME variable on the WinCC client you can determine the server with which it is connected. Notes on this are also available in Entry ID 11768430.

There should always be one server  master (@RM_MASTER = ´1´) and the other slave (@RM_MASTER = ´0´). If there is no network connection between the servers, then no master can be defined. If this connection is cut in running operation, the following rule holds: "Master remains master, slave remains slave".

The top priority here is that there must never be two masters.