I-O Display Systems Basic I/O Product - Manual (Page 49)

Introduction 1
1-3(Vol.2)
Protocol Compatibility:
The BASIC I/O AD instruction set core complies 100% with that of the OPTO- 22 Optomux
™ . With this ASCII character, speak-only-when-spoken-to protocol, a Host transmits inquiry
requests to the BASIC I/O AD to determine the status of its various process inputs. Similarly,
the software in the Host computer makes control decisions and transmits instructions to the
BASIC I/O AD, which in turn, makes the proper changes to its various outputs. Both the Host
and its communications link are essential elements in this data acquisition and process control
scheme.
Originally the protocol only allowed for all analog or all digital I/O chassis. Depending on
application requirements, each BASIC I/O AD can respond to pup to three different function
addresses. With their abbreviations they are:
MC Master Unit Control function address
MD Master Unit Digital I/O function address
MA Master Unit Analog I/O function address
It is this multiple function addressing capability of BASIC I/O ADs that allows them to
utilize, without modification, software developed for competitive products. Similarly BASIC
I/O ADs can operate simultaneously on the same network with these products.