Visual simulator. Network preparation and checks

No special hardware is required, only standard computer components. The list is as follows :

Computers are connected to each other via a switch



by network cables RJ45

Each computer in the network is identified by its network name and/or its IP address which can be specified.
Go to "Start"->"Settings"->"Control panel"->"Network Connections"-> "LAN or High-Speed Internet"->"Local Area Connection"->"General"-> "Properties"->"Internet Protocol(TCP/IP)"->"Properties" to specify each computer IP address. For local area network it is usually set like
192.168.1.XXX, where XXX is computer number unique for your LAN. Click on Subnet mask, it will be set to proper values.

IP address information can be obtained at any time by going to Start->Run->cmd and then

>ipconfig

from command line.

Test that network exchange is OK. It can be tested with (run from command line - use "Start"->"Run"->cmd.exe)

>ping IP_or_network_name_of_other_computer

If replies are present, network is OK, but firewalls may silently block creation of network sockets.

It may be necessary to turn firewalls off to let network exchange work. Each Windows version and its updates produce new and hardly explainable behaviour of its firewalls. Earlier Windows firewall gracefully asked if to allow creation of network sockets for a specific application, but at some moment it stopped. With Windows 7 it seems to work well again.
So, if network is not working, it is most likely due to a firewall. You can enable/disable Windows firewall in "Start"->"Settings"->"Control panel"->"Security center", the on/off button is at the very bottom.
Other firewalls normally block network exchange without saying a word. Look for them in "Start"->"Settings"->"Control panel"->"Administrative tools"-> "Services". Click the right mouse button to set its properties ("Stop" or "Start manually").

The server has a set of network tests modelling typical network operations used by the simulator. Show server window by clicking its icon on the taskbar:



The server window appears:



To make a test, select a computer from the above list - and the [Test] button becomes enabled. Click this button. The server connects to the selected computer ("pings") - sends some random data and awaits for a reply. The three checks are the following.
UDP exchange is the basic mechanism to broadcast commands and maintain a distributed database of attributes over network. If it fails, nothing will work. This is a very strong failure. It may happen if there is no cable connection or server is not running on target computer (see the above pictures - it should display the server icon on the taskbar). Or a firewall blocks everything.
The second test is TCP/IP test. This type of network exchange is used to transfer large amounts of data between computers, like digitized voice between radio stations. The possible reasons for it not working are the same as for the UDP failure - most likely a firewall.
A failure of the third test means that the program is unable to write (or rewrite) a file onto the hard disk. The reason may be insufficient logon rights (try to logon as administrator) or file sharing or access to a folder.