Keithley 2302 Instruction Manual page 82

3-20 Pulse Current Measurements
Table 3-3
PCURrent FAST, SEARch, and DETect commands
FAST SEARCH DETECT
ON ON ON
ON ON OFF
ON OFF ON
ON OFF OFF
OFF OFF ON
OFF OFF OFF
Shaded cells designate command with precedence in each mode.
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DESCRIPTION
The unit is most responsive to bus commands in this mode. The supply does
not wait for TOUT or search time for background pulse current readings and
TLEV command checks. Front panel displays FAST HI / LO / AVG (in remote
mode) instead of PCUR HI / LO / AVG (if in local mode). The bottom line may
show a previous reading or dashes based on what commands were sent previ-
ously when in remote mode.
With FAST set to ON, no pulse detection between user-triggered readings
occurs, no checking for the parameter of PCUR TLEV commands to detect a
pulse occurs, no setting of the pulse trigger timeout bits in the status model
between user-triggered readings occurs. Front panel has no indication that
pulse is not detected. Over the bus, an overflow reading indicates no pulse
detected when asked for a user triggered reading.
For triggered readings, the PTT (Pulse Trigger Timeout) bit is latched until
read so the bit may still be set in the status model from a previous timeout. (See
section 8 on the status model for more information-Model 2306 User's Man-
ual.) For triggered readings, the PTT (Pulse Trigger Timeout) bit will be set if
the reading times out and the pulse is not detected.
The unit is more responsive to bus commands in this mode since the supply
does not need to wait for TOUT or search time for pulse current background
readings. However, the supply does need to wait for TOUT or search time
when checking the parameter setting for TLEV commands. Refer to
4. Front panel displays "NO SEARCH" instead of PULSE HI / LO / AVG. The
bottom line may show a previous reading or dashes based on what commands
were sent previously when in remote mode.
The setting of the pulse trigger timeout bits in the status model will only occur
between user-triggered readings if TLEV commands are sent. For triggered
readings, the PTT (Pulse Trigger Timeout) bit will be set if the reading times
out and the pulse is not detected. Also, since the PTT bit is latched until read,
the bit may still be set in the status model from a previous timeout. (See section
8 on the status model for more information-Model 2306 User's Manual.)
Figure 3-