IP Address

Basics

To establish the communication between two technical devices, each device must be capable of sending data to the other device. This data can only be received by the intended remote station if it has been addressed properly. In IP networks, this is ensured by specifying an IP address.

An OPC server is able to address a PLC directly by its IP address. Example: 192.168.1.20

It is also possible to address a PLC by its name. For this purpose, specify the name of the PLC and the corresponding IP address and enter the domain server in the TCP/IP settings of the server. For a domain name (e.g. “PLC1”), the server queries the name server to get the IP address and then addresses the PLC directly using its IP address (192.168.1.20).

IP Address

Each IP data packet starts with an IP header. This is an information section used for transmission on the IP layer. This header also includes two fields where the IP addresses of both the sender and the receiver are entered before transmitting the data packet. Routing is done on layer 3 of the OSI model, the network layer.

IPV4

The IPv4 addresses that have been used predominantly since the introduction of Internet Protocol Version 4 consist of 32 bits, i.e. 4 octets (bytes). This means that it is possible to represent 232 = 4,294,967,296 addresses. In dotted decimal notation, the four octets are written as four integers, from 0 to 255, in decimal format, separated by dots.

Example:    192.168.1.20.

Actually all IPV4 addresses are occupied. New systems will need an IPV& address.

IPV6 – new version with a bigger address space

Due to the rapidly increasing IP address demand, it was foreseeable that the usable address space provided by IPv4 would soon be exhausted. The IANA address pool was depleted on February 03, 2011. This was the main reason for developing the IPv6 protocol. IPv6 uses 128 bits to store addresses. This means that 2128 = 25616 (= 340,282,366,920,938,463,463,374,607,431,768,211,456 ≈ 3.4 · 1038) addresses can be represented. This number is sufficient to provide each square millimeter of the surface of the earth with at least 665,570,793,348,866,944 (= 6.65 · 1017) IP addresses.

Since a decimal representation with ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd.ddd would neither be very transparent nor handy, IPv6 addresses are usually represented in hexadecimal format. To further simply this representation, every two address octets are grouped and separated by colons. XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX.

Example:     2001:0db8:85a3:0000:0000:8a2e:0370:7344

To further shorten the string, leading zeros in a block can be omitted.

A sequence of blocks consisting only of zeros can be replaced with :: but only once in each IPV6 address.

Example:     2001:db8:85a3::8a2e:370:7344

For IPV6, usually names are specified instead of the IP addresses.

Domain Name

An IP station can be accessed over a domain name. Ask your system administrator. Possibly he has done this.