6 - 2 THE CPL PROTOCOL
There are several IMPLICIT QUERY commands, which means that the
oscilloscope will send data back (i.e., respond) to the computer after receiving
and executing the command.
Acknowledge
The <acknowledge> is an automatic response from the oscilloscope to let the
computer know that the received command has been executed. The
<acknowledge> also contains information about how the command was
executed.
An <acknowledge> is always followed by a CR
. For more information, see section
6.6 ACKNOWLEDGE
.
Responses
The format of the response data depends on the command which invoked the
response. When several values or strings are returned they are always separated
with a RESPONSE DATA SEPARATOR which is a comma ("," = ASCII 44). To
signal the end of the response a RESPONSE MESSAGE TERMINATOR
CR
(ASCII 13) is sent.
Data Separators
Data Separators are used between parameters sent to the oscilloscope and
between values and strings received back from the oscilloscope. The following list
gives the possibilities for data separators:
program data separator
space SP
(ASCII 32)
*
)
tab HT
(ASCII 9)
*
)
comma , (ASCII 44)
*
) more than one space or more than one tab can be used as a
separator
response data separator
comma , (ASCII 44)
Message Terminators:
At the end of a command or response a terminator must be sent. For both
programming and response messages the terminator has been defined as:
program message terminator
carriage return CR
(ASCII 13)
response message terminator
carriage return CR
(ASCII 13)