Bsap

Product Data Document
454ds-6a August 31, 2007 - Page 1

Bristol® BSAP
Bristol Standard Asynchronous/Synchronous Protocol
Features
• • • • • • • • • • • • • Compatible with SCADA and LAN networks ISO 1745/2111/2629 compliant Tree topology network Up to 6 network levels Up to 127 nodes from each node at a level Polled network Local and global addressing Peer-to-peer and RDB modes Report byexception Alarm handling Network time synchronization 16 bit CRC-CCITT error checking Communication statistics and diagnostics

Bristol® Standard Asynchronous/Synchronous Protocol (BSAP), from Emerson Process Management, provides a complete communication framework for all Emerson’s Bristol Network 3000 and ControlWave® products. It is a poll oriented communication system for horizontal LAN aswell as vertical, multi-layer networks. Consequently, BSAP is equally well suited to both synchronous high speed local networks and asynchronous low speed wide area networks. BSAP is able to offer extremely high message security, required for phone line and radio networks, through the use of 16 bit CRC-CCITT error checking, handshaking, and extensive communication statistics reporting. The pollingscheme employed by BSAP ensures that each node in the network has an equal opportunity to be polled and to respond. In addition, no node can dominate the network communication. BSAP supports both local and global addressing to all Network 3000 or ControlWavenodes in a network.

Network Topology
At the top of the network is the network master or host, typically a personal computer or mini computerperforming graphical user interface functions. The network master normally connects to one (or sometimes more) Bristol process controllers commonly referred to as a data concentrator or communications front end. It in turn becomes a master node to up to 127 slave nodes. Each of those can then be a master to another level of slave nodes.

Remote Automation Solutions
Website:www.EmersonProcess.com/Remote

Product Data Document
454ds-6a August 31, 2007 - Page 2

Bristol® BSAP Protocol

Remote Automation Solutions
Website: www.EmersonProcess.com/Remote

Product Data Document
454ds-6a August 31, 2007 - Page 3

Bristol® BSAP Protocol
Peer to Peer Communication
Peer to peer communication is a mechanism for transferring data blocks, such as signal lists and data arrays,between any two adjacent nodes in a network. Peer to peer uses Master/Slave and Client/Server software modules which should not be confused with BSAP master/slave communication. A BSAP slave may have a Master module and a BSAP master may have a Slave module. Master modules execute periodically at the rate of the program task in which they are included. Once a Master module executes the message requestis passed off to BSAP for communication. Slave modules execute asynchronously with respect to tasks. When a command is received from a Master module, it is executed immediately.

This hierarchy can extend up to six levels deep. Each intermediate node has both master and slave capability through separate communication ports. This architecture lends itself very well to the typical geographicaldistribution of controllers in most SCADA system applications. It also allows multiple asynchronous communications to occur throughout the network since each network branch can communicate simultaneously.

Local and Global Addressing
The computer at the top of the network has the ability to communicate locally to its attached node or through it to any other node in the network. In addition, acomputer attached to a lower level node, through a Pseudo-slave port, can have access to any data, except alarms, in any other node in the network. This computer will have access to alarms from its attached node and any nodes below it. Each Bristol process controller can actually support multiple personal computers. In some systems it is convenient to have all data from all nodes collected by the...