CF 126
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Nov 2001
relating to this functionality will not work with it. If a command is not available on such an instrument, it will
be mentioned in the description for that command.
Likewise, if your instrument is not equipped with an optional Relay/DAC channel, commands relating to
relays and DAC outputs will not work on your instrument.
3.4 Two Types of Commands
3.4.1 System Commands
System commands are commands that apply to the entire instrument. For example, since the instrument
has one serial communications port all commands that apply to serial communications are system
commands.
3.4.2 Channel Commands
Channel commands are those that affect the operation of only one particular channel. For example, if the
full-scale range of a Strain Gage Input channel is altered, it applies only to a single channel of the
instrument and not the entire instrument.
3.5 Addressing
Every instrument on the communications loop must have a unique two-character address. As shipped
from the factory, every DFI has an address of "00" (ASCII codes decimal 30, decimal 30). This address
can only be viewed, not changed, from the front panel. An instrument's address can only be changed over
the serial communications link. For details on addressing, see "Addressing".
3.6 Command Format
3.6.1 Format
An example command is shown below:
#0002WK0169.89
↵
where:
#
is called the
attention
character, which alerts all instruments that a command is being
transmitted to them. This character is ASCII code decimal 35.
00
is the two-character
address
of the SC to be communicated with. Each character must
be a number or an uppercase letter.
02
is the two-numeric-ASCll-character
channel number
to which this command will apply.
When using system commands that affect the entire instrument, the channel number can
be "00" (zero, zero) or it can be omitted altogether.
WO
is the two-character
command
to be executed. A list of the valid system commands is
given at the beginning of "System Commands". Lists of the valid channel commands are
given at the beginning of the remaining chapters.
01
is an optional two numeric character
parameter number
needed by some commands.
69.89 is the optional argument to be written to the instrument.
↵
represents the carriage return (ASCII code decimal 13), which indicates the end of the
command.
For example, the system command string
“#00W12400
”, followed by a carriage return, will cause the
instrument addressed as "00" to process the "W1 " command with a data value of "2400". The W1 system
command changes the baud rate 2400 baud.
An example of a channel command string is
“#0301F1
”, This command, followed by a carriage return,
causes the instrument addressed as "03" to process the "F1" command on channel "01 ". The "F1"
command activates the tare function, and thus this command string activates the tare function for channel
01.
