Browse Prior Art Database

Connecting Multiple Programmable Controller Remote Nodes Via a Ring Architecture

IP.com Disclosure Number: IPCOM000046152D
Original Publication Date: 1983-Jun-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 3 page(s) / 44K

Publishing Venue

IBM

Related People

Davis, GT: AUTHOR

Abstract

A ring architecture communications network is used to tie multiple programmable controllers together to enhance the power and flexibility of an industrial automation system. Thus, resources are shared among several programmable controllers. Extention of local control programs to include variables monitored at other nodes is also included. To take full advantage of this, the controllers at the individual nodes should all be the same type, or at least have similar instruction formats. To the basic instruction format at each node is added a field to define which node will execute the instruction. The instruction to be executed is then transmitted to the appropriate node for execution, with the result being sent back to the original node, if required.

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Connecting Multiple Programmable Controller Remote Nodes Via a Ring Architecture

A ring architecture communications network is used to tie multiple programmable controllers together to enhance the power and flexibility of an industrial automation system. Thus, resources are shared among several programmable controllers. Extention of local control programs to include variables monitored at other nodes is also included. To take full advantage of this, the controllers at the individual nodes should all be the same type, or at least have similar instruction formats. To the basic instruction format at each node is added a field to define which node will execute the instruction. The instruction to be executed is then transmitted to the appropriate node for execution, with the result being sent back to the original node, if required. A single node in a system can then potentially have access to all of the facilities at each of the other nodes in the network.

A key characteristic of a ring network is that any node can communicate with any other node without the intervention of a host. This capability makes it the ideal medium for sharing the controlling and processing capabilities of devices at remote nodes, since host performance is not degraded by interactions among other nodes. However, the host provides resource management assistance. If used to help develop application code, the host can modify the instruction fields defining which node will execute each instruction. In this way resources are distributed according to need, without the user being required to worry about the details.

The drawing illustrates a system in which several remote nodes can all control pieces of the same process. The system includes three programmable controllers 1-3 serving as nodes #1-#3, respectively, a host computer 4, such as the IBM Series/1 computer, serving as node #0, and a ring network 5. An input instruction at one node is passed to a second node for execution, with the resulting input sample being passed back to the first node for use in solving a control equation. Likewise, an entire piece of the control equation can be solved at the second node, with a single result passed back to the first node to be used in a higher level co...