Fluke 225C Programming Reference Manual page 110

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The ScopeMeter returns an <acknowledge> reply after
each command or query. The value indicates correct or
incorrect operation. You always must read this reply to check
for the correct operation and to achieve synchronization
between your program and the RS232 interface of the
ScopeMeter.
<acknowledge>
VALUE
0
1
2
3
4
Note: The ST query may give you additional information.
When the ScopeMeter detects an error during the
execution of a command, it sends the corresponding
<acknowledge> reply, terminates further execution of the
command and will be ready to accept a new command.
Syntax Error
Returned when the command is not understood by the ScopeMeter
for one of the following reasons :
- Unknown header
- Wrong instructions
- Data format of body is wrong, e.g. alpha characters when
decimal data is needed.
Execution Error
Returned when internal processing is not possible because of
one of the following reasons:
- Data out of range
- Conflicting instrument settings
Page A.1
APPENDIX A
MEANING
No Error
Syntax Error (see Note)
Execution Error (see Note)
Synchronization Error
Communication Error
ACKNOWLEDGE DATA