Keithley 2302 Instruction Manual page 83

Table 3-3
PCURrent FAST, SEARch, and DETect commands (cont.)
FAST SEARCH DETECT
OFF ON ON
OFF ON OFF
Shaded cells designate command with precedence in each mode.
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DESCRIPTION
This mode allows the user to know whether the pulse disappeared before a
user-triggered reading is requested. The responsiveness of bus commands is
governed by TOUT (if no pulses are detected), or by search time (if pulses are
detected). Therefore, the longest response time to bus commands is approxi-
mately the greater of either TOUT or search time values. Refer to
If the pulse is detected, the front panel will display DETECT HI / LO / AV on
the top line of the display. If no pulses are detected, the front panel will display
"NO DETECT" as well as the PTT (Pulse Trigger Timeout) bit being set in the
status model. Since the PTT bit is latched until read, a query for the PTT bit
may indicate that pulse trigger timeout occurred although the display is show-
ing DETECT. (See section 8 on the status model for more information-
Model 2306 User's Manual.) The bottom line may show a previous reading or
dashes based on what commands were sent previously when in remote mode.
Checking for the parameter of PCUR TLEV command may set the PTT bit of
the status model. For triggered readings, the PTT (Pulse Trigger Timeout) bit
will be set if the reading times out and the pulse is not detected.
With DETect OFF, background pulse current measurements will occur between
user-triggered readings as well as pulse detection. If the pulse is detected, the
front panel will display PULSE HI / LO / AVG on the top line of the display
along with the reading on the bottom line. If no pulses are detected, the front
panel will display "NO PULSE" as well as the PTT (Pulse Trigger Timeout) bit
being set in the status model. Since the PTT bit is latched, a query for the PTT
bit may indicate that pulse trigger timeout occurred although the display is
displaying PULSE HI / LO / AVG and a reading. (See section 8 on the status
model for more information-Model 2306 User's Manual.) Checking for the
parameter of PCUR TLEV commands to detect a pulse may set the PTT bit. If
detecting pulses, the supply's responsiveness to bus commands is affected by
search time. If not detecting pulses, the supply's responsiveness to bus
commands is affected by TOUT. Therefore, the longest response time to bus
commands is approximately the greater of either TOUT or search time (refer to
Figure 3-4).
In this mode, the front panel will show PULSE HI / LO / AVG on the top line
with a reading on the bottom. Checking the parameter of PCUR TLEV
commands to detect a pulse may set the PTT bit of the status model if TLEV
setting causes no pulse detection. For triggered readings, the PTT (Pulse
Trigger Timeout) bit will be set if the reading times out and the pulse is not
detected.
Pulse Current Measurements
Figure
3-21
3-4.