ProSoft Technology MVI56-BSAPS - Manual (Page 57)

Reference MVI56-BSAPS ♦ ControlLogix Platform
Bristol Babcock Serial Slave Module
ProSoft Technology, Inc. Page 57 of 83
September 22, 2008
Configurable parameters include:
Parameter Value
Analog Input Count 0 to 255
Logical Input Count 0 to 255
String Count 0 to 30
Slave Address 1 to 255
Baud Rate 110 to 115,200
Parity None, Odd, Even
Data Bits 5 to 8
Stop Bits 1 or 2
RTS On and Off Timing 0 to 65535 milliseconds
Minimum Response Delay 0 to 65535 milliseconds
Use of CTS Modem Line Yes or No
5.2 Functional Overview
This section provides an overview of how the MVI56-BSAPS module transfers
data using the BSAP protocol. You should understand the important concepts in
this chapter before you begin installing and configuring the module.
5.2.1 Introduction
The Bristol Babcock Asynchronous Communication Protocol (BSAP) is the
foundation for a proprietary network that has a tree structured topology. This
open-ended topology supports a variety of configurations which may include one
or more nodes at each of up to six levels. Messages can be sent between nodes
on the same level or on different levels. Each message is uniquely identified and
has an error checking code associated with it. MVI56-BSAPS supports only
bottom level, one to one communication.
BSAP operates in a polled environment. Each link in the network supports a
different poll rate. The rate selected depends on a variety of application-
dependent factors.
BSAP has been designed and implemented according to the functional layers of
the International Standards Organization (ISO) model. Because each layer is
independent of its adjacent layers, both synchronous and asynchronous
transmission modes can be supported. MVI56-BSAPS supports only
asynchronous transmission mode.
5.2.2 Protocol Overview
ƒ Variable message length to 253 bytes
ƒ Analog Floating-point (4 bytes)
ƒ Logical data (1 byte)
ƒ Packed logical data (8 bits/byte)
ƒ Alarm time stamp (5 bytes)
ƒ Alarm data (6 - 10 bytes)