Keithley 6514 Instruction Manual page 216

16-6 DISPlay, FORMat, and SYSTem
For example, assume the instrument is configured to perform 10 measurements and send
them to the computer using the binary format:
Bytes = 2 + (10 x 4) + 1
B) FORMat:ELEMents <item list>
Parameters
The specified elements are included in the data string in response to :FETch?, :READ?,
:MEASure? and :TRACe:DATA?. Note that each element in the item list must be separated by
a comma (i.e. send ":ELEMents READing, TIME, STATus" to include all elements in the data
string. The elements for the ASCii format are shown in Figure 16-1.
An overflow reading is returned as +9.9E37. When a specified data element has invalid data
associated with it, NAN (Not A Number) will be the response. NAN is returned as +9.9E37.
Timestamp — Timestamp references the returned data string to a point in time. The times-
tamp operates as a timer that starts at zero seconds when the instrument is turned on, or when
the timestamp is reset (SYSTem:TIME:RESet). After 99,999.99 seconds, the timer resets back
to zero and starts over.
For buffer readings, timestamp can be referenced to the first reading stored in the buffer
(absolute format) which is timestamped at 0 seconds, or to the time between each stored reading
(delta format). The TRACe:TSTamp:FORMat command is used to select the timestamp format.
Status — The status word provides information about Model 6514 operation. The 16-bit sta-
tus word is sent in decimal form. The decimal value has to be converted to the binary equivalent
to determine the state of each bit in the word. For example, if the returned status value is 9, the
binary equivalent is 00000001001. Bits 0 and 3 are set. The bits are explained as follows:
Bit 0 (OFLO) - Set to 1 if measurement performed while in over-range (overflowed reading).
Bit 1 (Filter) - Set to 1 when measurement performed with the averaging filter enabled.
Bit 2 (Math) - Set to 1 when measurement performed with CALC1 enabled.
Bit 3 (Null) - Set to 1 if null for CALC2 is enabled.
Bit 4 (Limits) - Set to 1 if a limit test (CALC2) is enabled.
Bits 5 and 6 (Limit Results) - Provides limit test results:
Bit 6 Bit 5
0
0
1
= 43
READing =
TIME =
STATus =
0 All limit tests passed
1 CALC2:LIM1 test failed
0 CALC2:LIM2 test failed
Voltage, current, resistance or charge reading
Timestamp
Status information