TCP Keep-Alive Messages

A Keep-Alive Message is a confirmation message or an "acknowledge". Therewith you can proof in the backround if a communication partner who established a connection, is still active and therefore is participating in the communication. If the communication partner should not be active anymore, the communication channel will be closed clearly and regular, to be free for a new attendant.

Keep-Alive can be configurated in the registration by the keys Keep-Alive-Time and Keep-Alive-Interval. The default value for the Keep-Alive-Time is set on two hours. The interval-time is set by default to one second. This is the time until there is a repetition of a not-answered Alive-request. All values are stated in milliseconds. If the corresponding key is not listed in the registration they need to be applied as follows. These are no TwinCAT-settings but specific settings of the operating system. Therefore you will find further information in the operating system documentation, e.g. at the Microsoft homepage.

Under Windows W2K, XP, Windows Embedded Standard:

In the folder HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\ an object with the name KeepAliveTime needs to be applied as DWORD. Therefore you need to insert under Edit -> New -> DWORD Value. If you set it to the value 0x4E20, this equates 20 seconds.
In the folder HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\ an object with the name KeepAliveInterval needs to be applied as DWORD. Therefore you need to insert under Edit -> New -> DWORD Value. If you set it to the value 0x1388, this equates 5 seconds.

Under Windows CE:

In the folder HKEY_LOCAL_MACHINE\Comm\TcpIp\Parms\ an object with the name KeepAliveTime needs to be applied as DWORD. Therefore you need to insert under Edit -> New -> DWORD Value. If you set it to the value 0x4E20, this equates 20 seconds.
In the folder HKEY_LOCAL_MACHINE\Comm\TcpIp\Parms\ an object with the name KeepAliveInterval needs to be applied as DWORD. Therefore you need to insert under Edit -> New -> DWORD Value. If you set it to the value 0x1388, this equates 5 seconds.