WAGO 750-341 Manual

Also see for 750 Series: Manual Manual Manual Manual Manual

Contents

Glossary ï 193WAGO-I/O-SYSTEM 750ETHERNET TCP/IPPort numberThe port number, together with the IP address, forms an unambiguousconnection point between two processes (applications).Predictable ETHERNETThe delay time of a message on an ETHERNET network can be predicted.The measures which have been taken in predictable ETHERNET make itvirtually possible to realize realtime requirements.Proxy gatewayA proxy gateway (or proxy server, too) allows systems which do not havedirect access to the Internet, indirect access to the network. These can besystems which are excluded from direct access by a firewall for securityreasons.A proxy can filter out individual data packets between the Internet and alocal network to increase security. Proxies are also used to limit access toparticular servers.In addition, proxy gateways can also have a cache function, in which casethey check whether the respective URL address is already available locallyand return it immediately, if necessary. This saves time and costs when thereare multiple accesses. If the URL is not in the cache, the proxy forwards therequest as normal.The user should not notice the proxy gateway apart from the singleconfiguration in the web browser. Most web browsers can be configured sothat they use different or no proxy gateways per access method (FTP,HTTP).RRepeaterRepeaters are physical amplifiers without their own processing function.They refresh data without detecting damaged data and forward all signals.Repeaters are used for longer transmission distances or when the maximumnumber of nodes of 64 devices per twisted pair segment is exceeded. Arequest from a client to server is a provision to act on a serivce or funtioncall.RequestA service request from a client which requests the provision of a servicefrom a server.ResponseThe serverís reply to a clientís request.