Section 5 Listner Input Formats
5-2
A program message is a sequence of program message units. Each unit is a program command or query.
The following figure shows that a program message made by connecting two program messages LOG 10 and RLV
–20 with a program message unit separator is sent from a controller to a device to set the log scale to 10 dB/div and
the reference level to –20 dBm.
sp <NL>
<PROGRAM DATA>
1Ø
Listener
(device)
Address15
Talker
(controller)
WRITE @1Ø8 : " LOG 1Ø ; RLV –2Ø " <NL>
LOG
<PROGRAM MESSAGE>
<PROGRAM MESSAGE UNIT>
<PROGRAM MESSAGE UNIT>
<PROGRAM MESSAGE UNIT SEP
ARAT
OR>
Listener address
specification
<PROGRAM MESSAGE TERMINATOR>
<TERMINATED PROGRAM MESSAGE>
RLV –2Øsp ;
<COMMAND PROGRAM HEADER>
LOG
<PROGRAM HEADER SEPARATOR>
<white space>
sp
<white space> <decimal numeric program data>
1Ø
<suffix program data>
None
<program mnemonic>
LOG
sp
<white space>
<COMMAND PROGRAM HEADER>
RLV
<PROGRAM HEADER SEPARATOR>
<PROGRAM DATA>
–2Ø
;
<white space>
NL
A program message is a sequence of functional elements, the minimum units that can represent functions. In the
above figure, functional elements are indicated by capital characters with them enclosed in < >. Functional elements
are further classified into coding elements which are indicated by lowercase characters with them enclosed in < >.
The chart indicating the route of selection of functional elements is called a functional syntactical chart. The chart
indicating the route of selection of coding elements is called a coding syntactical chart. On the following pages,
program message formats are explained using these functional and coding syntactical charts.
Coding elements indicate coding of the actual bus which is required to send functional element data byte to a device.
Upon receipt of a functional element data byte, the listener checks whether individual elements follow the coding
syntax rules. If they do not follow the rules, the listener causes a command error without regarding the elements as
functional elements.
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