3
DESCRIPTION
ENGLISH
STANDARD Communication Protocol
3. DESCRIPTION
3.1 Communication
The protocol specifi cations defi ne the data sequence, the programming sequence and the check
codes, necessary for a proper data communication.
This protocol allows the communication between the PC (master) and the instrument (slave).
The protocol uses an half duplex connection on a single line. In this way, the communication
messages move on a single line in two opposite directions.
It is not possible a communication between instruments, without PC, as they cannot send comman-
ds; instruments are limited to reply. All the trasmitted characters are part of the ASCII code (see
chapter 5).
3.2 Identification Code
In a multi-point type connection, a code allows to identify each instrument during the communi-
cation. This code, the Serial Number, is assigned to each instrument by the manufacturer.
It is made of 9 characters (numbers and letters), printed on the instrument label.
A second identifi cation code, the Logical Number, can be assigned by the user. As it is made up
of 2 ASCII characters ($01...$FF), it allows a faster communication.
The Logical Number can be changed at any time using the specifi c command (see section 4.3).
The instrument is supplied with a $01 Logical Number.
NOTE
The $00 Logical Number is used for broadcast commands. A command with
the $00 Logical number is received by all the instruments connected in the
network.
