Thursday, July 21, 2011

Network and Operator Interface of EPICS PLC

The Ethernet of Redundant gigabit with fiber optics connected like as a "star" initiating from the CCR (central control room) to every accelerator such as 50-GeV PS, 3-GeV RCS and Linac, and the facility of experimental is the control network backbone. The star like the optical fiber cables of 100baseFX expand to network switches over the facility from every the station of backbone. The majority of the network end joins for instance IOCs are 100baseTX. Some of the nodes in a high EMI noise levels for example close to high powered pulsed power supplies or klystrons should be 100baseFX. They are going to use the connections of Ethernet in stead of other area buses. As a result the total number of IP addresses needed for the control system could simply go beyond a few thousands. For that reason it is impossible to apply a space of global IP address. As an alternative they are going to exploit a space of Class B private IP address and use a router to communicate to outside of the network.

They have not figured out how the network should be separated into subnets. The channel access (CA) of EPICS protocol needs the network broadcast. As a result all nodes of EPICS should be in one subnet. Nodes for diagnostic purpose should be in the right place to a different subnet because they have to be free from the subnet of EPICS. Such diagnostic nodes comprise a port of communication for a traffic watcher, of course, it should have also a port in the subnet of EPICS to search out network traffic and an IOC’s CPU console such as RS232c throughout a terminal server. Those two kinds of nodes are in general close each other in space, and consequently it is better to realize the technique of virtual-LAN to decrease cabling and network switches number.

Operator interface
They will use one of the requirements of EPICS OPI tools for the operation of EPICS, but not specific yet which one should be applied. Also there are two options; (1) the applications of OPI work directly on a PC Linux or (2) the applications of OPI work on an X-client machine with a PC with X-server or an Xterminal. The first option is good for traffic network but not good for applications of maintaining. The later is just opposed. Another operator interface type is required which is associated to the some issues.


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