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92 L4400 User’s Guide
3 Operating and Programming
• When a sequence is defined, the specified commands are checked for
proper syntax and absolute parameter range limits. If an error is detected
during compilation, the entire sequence will be discarded. More extensive
error checking, such as channel range expansion and validation, is
performed when the sequence is executed.
• If you define a sequence with a name already in use by another sequence,
the new definition will overwrite the previous definition (no error is
generated).
• A sequence name can contain up to 30 characters. The first character
must be a letter (A- Z), but the remaining 29 characters can be letters,
numbers (0- 9), or an underscore ( _ ). Blank spaces are not allowed.
• When stored in memory, the user- defined sequence names are converted
to all uppercase letters. For example, when stored “MySeq_1” is converted
to “MYSEQ_1”.
• A sequence may invoke another sequence, but may not invoke itself
recursively. In addition, the number of invocations is limited to four levels
of nesting and this is enforced at the time of execution. Exceeding the
limit will abort the sequence and an error will be generated.
• At the time of sequence definition, a sequence may reference another
undefined sequence; however, at the time of execution an error will be
generated if an undefined sequence is invoked.
• Up to 500 unique sequences can be stored in non- volatile memory. Each
sequence is limited to 1024 bytes.
• While a scan is running (see “Scanning Applications" on page 69), the
instrument prevents use of all channels in banks that contain one or
more channels in the specified scan list (these channels are dedicated
to
the scan). Therefore, if a sequence attempts to operate a channel in
a scanned bank, an error is generated and the entire sequence will
be discarded.
• If the command overlap function is enabled, all switching operations
within the sequence follow the overlapping rules. If the command overlap
function is disabled, all commands within the sequence are processed in a
serial fashion in the exact order in which they are received. Note, however,
that within a single command containing a <ch_list> parameter (e.g.,
ROUT:CLOSE (@1001:1010)), the order of the individual switch
operations is not guaranteed.
The following command defines a sequence named “MYSEQ_1”, which closes
several channels on the instrument and then opens a single channel.
ROUT:SEQ:DEF MYSEQ_1,"ROUT:CLOS (@1001:1009);OPEN (@1001)"