Keithley 2002 User Manual page 205

IEEE-488 Reference
Program fragment
Parameters
3-82
RNUMber: The instrument keeps track of the number of readings it has performed. This reading
counter starts at zero when the instrument is turned on or when :SYStem:RNUMber:RESet is
sent over the bus. When a reading is sent over the bus (i.e. :FETCh?), the RNUMber element
indicates the reading number. The instrument also keeps track of the number of readings it has
stored in the buffer. When buffer readings are sent over the bus (:TRACe:DATA?), each reading
number is referenced to the first reading, which is #0, stored in the buffer. If using Pre-trigger to
store readings, the pre-trigger readings are assigned negative numbers.
UNITs: This element attaches the function unit to the reading, the time unit (sec) to the times-
tamp, and the channel unit (internal or external) to the channel number. An internal channel
refers to an internally installed switching card (such as the Model 2001-SCAN) channel, while
an external channel refers to the channel for an external switch system. This element is not avail-
able for the binary formats.
TIMEstamp: A timestamp is available to reference each reading to a point in time. There are two
basic types of timestamps; real-time timestamp and relative time timestamp. The real-time
timestamp provides the time (24-hour clock format) and date for each reading sent over the bus.
The relative timestamp operates as a timer that starts at zero seconds when the instrument is
turned on or when the relative timestamp is reset (:SYSTem:TSTamp:RELative:RESet). The
timestamp for each reading sent over the bus is referenced, in seconds, to the start time. After
99,999.999999 seconds, the timer resets back to zero and starts over.
Timestamp is also available for buffer readings. Timestamp can be referenced to the first reading
stored in the buffer (absolute format) which is timestamped at 0 seconds, or can provide the time
between each reading (delta format). The :TRACe:TSTamp:FORMat command is used to select
the absolute or delta format. For the delta format, real-time timestamp is expressed as the days,
hours, minutes and seconds between each reading, while the relative timestamp is expressed as
seconds between each reading. When using the absolute format for the relative timestamp, any
pre-trigger readings will have a negative timestamp.
STATus: This element indicates if the reading is normal (N), overflowed (O) or referenced (R)
to another value. This element is not available for the binary formats.
The ASCII format shown in Figure 3-18 shows the byte order of the data string. Keep in mind
that the byte order can only be reversed for the binary formats.
When using this command to add an element, you must include all elements that you want in
the format. For example, if the reading is already specified and you want to add the time-stamp,
you must include the READing parameter.
:form:elem time, read
Data elements for the item list can be listed in any order, but are always sent in the order shown
in Figure 3-18.
PRINT #1, "output 16; :form:elem read, stat, unit; elem?"
PRINT #1, "enter 16"
:BORDer <name>
:FORMat:BORDer <name>
<name> = NORMal
SWAPped
Specify binary byte order
Normal byte order for binary formats
Reverse byte order for binary formats
' Specify elements
' Get response mes-
sage from 2002