Several requirements must be fulfilled in the configuration of your Windows environment in order to enable multi-user operation of WinCC. If the settings required for this are not correct, there is no guarantee that WinCC functions error-free in multi-user mode or whether it is at all possible.
Make the settings below on your computer to meet the requirements for multi-user operation.
1. IP addressing (TCP/IP)
The IP addressing is the basis for a working logical network. Ensure that the computers to be networked are in a physical and a logical network.
In order to fulfill this condition, you must think about how to structure you network already when assigning the IP addresses. It is not possible for two computers from different logical networks or subnetworks to communicate if you are not using a router.
The network address and subnet mask define the association of a computer to a logical network.
Network address: it is not the IP address of a computer that is meant here, but the address of the network, in other words, just a part of the character string.
There are three different classes of network addresses:
Table 1: Network addresses with TCP/IP
||Example of a network address in the range
||Standard subnet mask|
Note on subnet masks and IP addresses
More information on the topic is available in the FAQ in Entry ID: 2073614.
The range of 127.X.Y.Z is reserved for loopback tests and interprocess communication and is not a reliable network address.
Example of a network address: 142.16.x.y | Network | Host |
This is an example of a Class B address. You can tell this from the address range which is from 128 to 191 for Class B. The first two tetrads correspond to the IP network address in this case.
In the case of different IP network addresses (142.16.x.y and 142.11.x.y, for example) you must make further preparations for the client-server operation, because you need a router (gateway) for different network addresses.
When using routers, it is absolutely necessary to read and apply the notes from the WinCC Information System in this path:
WinCC Installation / Release Notes > WinCC Release Notes > Notes on Operation > Network Technology and UPS.
You can test correct computer addressing with the ping command.
For this you open the input prompt (Start > Run... > cmd) and execute the "ping + IP address" command (ping 188.8.131.52, for example) for each other computer.
If you do not get a response, you must check the complete network configuration and parameterization.
2. Name resolution
If you are not using a DHCP service in conjunction with DNS in your network which does this task automatically, you must configure the "lmhosts" file for name resolution. If you are using a DNS and WINS server, the system also does the name resolution.
The "lmhosts" file is in the path below in Windows:
Open the file with the text editor and enter all the computers that can be reached in the network according to the example in the file. Delete the comments above the entries and then save the changes in the file.
Make these changes on all the computers.
In order to continue optimizing the name resolution, write the keyword "#PRE" after each entry (standard maximum of 100 entries). Entries with this keyword are buffered in the cache right at system start. In the case of IP address resolution, the cache is read out first and then the lmhosts file if not all of the computer names can be resolved.
Fig. 01: The "lmhosts" file after configuration
In large networks, in addition to the "lmhosts" file you should also configure the "hosts" file from the same directory in order to accelerate name resolution.
A detailed description of the "lmhosts" file is available at the Microsoft internet sites below.
You can perform another ping command to test whether the changes have been applied.
Open the input prompt (Start > Run... > cmd) (Start > Run... > cmd) and execute the "ping + computer name" command (for example, ping WINCCPC01) for all the computers that you entered in the "lmhosts" file in the previous step.
If you get a response and the computer name has been resolved in the associated IP address, the file is configured correctly and the name resolution works in the network.
All SIMATIC WinCC stations must be logged on in the same workgroup or in the same domain.
3. Operating system
Which version of SIMATIC WinCC requires which operating system is given in Entry ID 21927773. (This also gives information about which WinCC client/server environments are possible.)
Which user rights are required for specific actions is given in the WinCC Information System at the link below.
WinCC Installation / Release Notes > Installation Notes > Requirements for the Installation > Access Rights in the Operating System.
If you install an update (formerly hotfix) or a Service Pack for WinCC, you should always read the Release Notes for this extension. Under certain circumstances the required user rights might change.
4. Terminal bus
The terminal bus must be configured for the right network card in the SIMATIC shell. If you are using multiple network cards there is the danger that the network card over which the WinCC communication is supposed to run is not selected here.
Notes on configuring the terminal bus are available in Entry ID 25437381.
Another indicator that the network is functioning (availability of the other computers) is that you can see the projects of the other computers in the network in the SIMATIC shell.
5. Order of network cards
The order of network cards defines the order in which the network services access the network cards. You must therefore ensure that the network card/connection (that you have selected as terminal bus) is in first place.
You make the settings in the path below: "Control Panel > Network Connections > Advanced > Advanced Settings... > Network Cards and Connections".
If you are using Windows 7 or Windows Server 2008, you must make settings in the Explorer window to get to this setting.
For this you switch to the Windows Explorer. Show the menu bar via "Organize > Layout". You can also have this menu bar displayed temporarily by pressing the "Alt" key.
Fig. 02: Display of the menu bar in Windows 7 and Microsoft Server 2008
Now, by way of the Control Panel, switch to the "Networks and Release Center". In the left window pane is the "Change adapter settings" button. Operate the button and then proceed with the "Advanced" step as already described above.
For the sake of security computers often have a firewall installed. Only the Windows firewall is released for operation with WinCC. If you activate this, you must then run the SIMATIC Security Control again and "Make settings". Port filters are generally not released.
More information about the distributed systems is available in the WinCC Information at the following link:
Configurations > Distributed Systems
If you are using WinCC version V5 or older, refer also to the notes in the document below. There you will also find notes on WINS, DNS and IPX.
WinCC_PCS7_lmhost_e.pdf ( 258 KB )
The functions and solutions described in this article confine themselves to the realization of the automation task predominantly. Furthermore, please take into account that corresponding protective measures have to be taken in the context of Industrial Security when connecting your equipment to other parts of the plant, the enterprise network or the Internet. Further information can be found in Entry ID: 50203404.
Network configuration, System requirements, HOSTS, LMHOSTS, LMHOST, DNS, WINS, IP address, Subnet, Subnet mask, 70775, 31385098, Client, Server