In the ‘open communication’ the communication takes place via the user program bymeans of handling blocks. These blocks are also part of the Siemens SIMATIC Manager.You will find these in the ‘Standard Library’ at ‘Communication Blocks’ .n Connection-oriented protocols:Connection-oriented protocols establish a (logical) connection to the communicationpartner before data transmission is started. And if necessary they terminate the con-nection after the data transfer was finished. Connection-oriented protocols are usedfor data transmission when reliable, guaranteed delivery is of particular importance. Ingeneral, many logical connections can exist on one physical line. The following con-nection-oriented protocols are supported with FBs for open communication via Indus-trial Ethernet:– TCP native accord. to RFC 793:During data transmission, no information about the length or about the start andend of a message is transmitted. However, the receiver has no means ofdetecting where one message ends in the data stream and the next one begins.The transfer is stream-oriented. For this reason, it is recommended that the datalength of the FBs is identical for the sending and receiving station. If the numberof received data does not fit to the preset length you either will get not the wholedata, or you will get data of the following job.– ISO on TCP accord. to RFC 1006:During data transmission, information on the length and the end of the messageis also transmitted. If you have specified the length of the data to be receivedgreater than the length of the data to be sent, the receive block will copy thereceived data completely into the receive range.n Connection-less protocol:There is thus no establishment and termination of a connection with a remote partner.Connection-less protocols transmit data with no acknowledge and with no reliableguaranteed delivery to the remote partner.– UDP accord. to RFC 768:In this case, when calling the sending block you have to specify the addressparameters of the receiver (IP address and port number). During data transmis-sion, information on the length and the end of the message is also transmitted. Inorder to be able to use the sending and receiving blocks first you have to con-figure the local communications access point at both sides. With each new call ofthe sending block, you re-reference the remote partner by specifying its IPaddress and its port number.6.5 Basics - IP address and subnetExclusively IPv4 is supported. At IPv4 the IP address is a 32bit address that must beunique within the network and consists of 4 numbers that are separated by a dot. EveryIP address is a combination of a Net-ID and a Host-ID and has the followingStructure: xxx.xxx.xxx.xxxRange: 000.000.000.000 to 255.255.255.255The Network-ID identifies a network res. a network controller that administrates the net-work. The Host-ID marks the network connections of a participant (host) to this network.The Host-ID can be further divided into a Subnet-ID and a new Host-ID by using a bit forbit AND assignment with the Subnet mask.The area of the original Host-ID that is overwritten by 1 of the Subnet mask becomes theSubnet-ID, the rest is the new Host-ID.Open communicationIP address structureNet-ID, Host-IDSubnet maskVIPA System MICRODeployment PG/OP communication - productiveBasics - IP address and subnetHB400 | CPU | M13-CCF0000 | en | 16-47144