TCP/IP System Settings

The TCP/IP system parameters represent the operating parameters in the TCP/IP core. The settings should only be changed in special cases. Please contact your system administrator before you make any changes to the settings.

Connect Request Time Interval (fast)

Short time interval between two CRs (Connect Requests).

The short time interval is used until the value set under Number of Fast CRs is reached.

Connect Request Time Interval (slow)

Long time interval between two CRs (Connect Requests). The long time interval is used after the value set under Number of Fast CRs was reached. This reduces the frequency of Connect Request attempts.

Number of Fast CRs

Specifies after how many failed Connect Request attempts the time interval between the attempts is increased so that the attempts are performed less frequently. As soon as the value specified here is reached, the Connect Request Time Interval (slow) is used between two Connect Request attempts. This allows reducing the network load.

Time Until Connection Is Lost

Time without data communication after which the connection is considered broken. Since TCP/IP as a WAN protocol normally does not use life acks, the connection is also broken if no data has been transmitted during the specified time.

Timeout Between the Acknowledges

Specifies the time after which an acknowledgment (ACK) is to be sent if no data traffic is taking place. For TCP/IP this value can be 0, which disables the life acks.

Time of the Acknowledge After Received Data

Received data is acknowledged after this time if no data frame has been returned. The shorter the time, the faster the data traffic, which is only in one direction.

Number of Retries

Specifies the number of retransmissions if no acknowledgment arrives from the receiver (confirming receipt of the data). When the specified number is reached, the connection is considered broken.

Timeout of an ARP Entry

Specifies how long entries in the ARP cache are valid if they have not been accessed. If an entry in the ARP cache is not accessed for a certain period of time, it will be removed. This behavior ensures that changes in the network can be detected and reflected by sending new ARP requests.

Timeout for DNS

Specifies the maximum time for converting a name to an IP address. When the timeout expires, the DNS request is retransmitted.

Time Between Two Life Data Acks

Time without data communication after which the connection is considered broken. Since TCP/IP as a WAN protocol normally does not use life data acks, the connection is also broken if no data has been transmitted during the specified time.

Maximum Frame Length

TPDU = Transport Protocol Data Unit

Specifies the maximum number of bytes that can be transmitted in a frame.

Start Number of the TCP Port Pool

Used for TCP connections in which a port has not been specified. If a port is parameterized as 0, a port number is generated. The numbers that are used start at the value given here.

Start Number of the UDP Port Pool

Used for UDP connections in which a port has not been specified. If a port is parameterized as 0, a port number is generated. The numbers that are used start at the value given here.

Factor for Timeout If No Header Is Used

All the timeouts given above are multiplied by this factor if no PLC header has been selected.

Factor for Timeout If RFC1006 Is Used

All the timeouts given above are multiplied by this factor if the RFC 1006 header has been selected.

Allow ICMP Broadcast

By default, modules ignore smurf attacks from the Internet (in other words, they do not reply). If ICMP broadcast frames are to be used in the LAN of a plant, you can select this check box to cause the module to reply.

Default

Resets all the input fields to the defaults.