KEPCO BOP 1000W, Operator'S Manual

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BOP-1K 080709
B-23
FIGURE B-8. USING LIST:WAIT COMMANDS TO CONTROL GENERATION OF A WAVEFORM MEASURED BY
MULTIPLE EXTERNAL DEVICES USING THE LOW-GOING LEADING EDGE OF AN EXTERNAL PULSE
B.82 [SOUR ce :]LIST:WAIT:LEDGE COMMAND
LIST:WAIT:LEDG
Syntax: Short Form: LIST:WAIT:LEDG value
Long Form: LIST:WAIT:LEDGe value
where:
<value> = programmed current (Amps) for current list, or programmed voltage (Volts) for voltage list.
Description: Waits for the leading edge of the trigger input to go low before proceeding to the next step. If
the trigger input is already low, the signal must go high then low for the leading edge to be accepted.
When the command is executed the output is immediately set to the <value>. Pins 1 (GND) and 3 of
the Trigger Port are used as the input trigger. If the trigger input goes from high to low (TTL logic 0 or
short-circuit) and a wait time has been established by LIST:SET:WAIT, the unit will proceed to the next
step when either a) the trigger input goes low or b) the wait time expires (non-zero wait values only),
whichever comes first. If the wait time is 0, the unit must wait until the trigger input goes from high to
low before proceeding to the next step.
This command must be preceded by LIST:CURR or LIST:VOLT command, otherwise a -221 “Settings
Conflict” error results. The entries of the dwell list must match the values in the current or voltage list,
otherwise a -226 “Lists Not Same Length” error results. (See Figure B-8.)
NOTES: 1. The power supply is assumed to be operating in constant voltage mode.
2. The WAIT commands provide a method to synchronize multiple instruments to a common con-
trol pulse. This example assumes BOP and a number of switching DVMs are connected to a
Unit Under Test (UUT). The DVMs are programmed to wait 1 millisecond after a low-going
edge is received from the host computer, then take a few measurements. The same low-going
edge is applied to the Trigger Input (pin 3 of the BOP Trigger Port); the negative-going edge of
this pulse will cause the BOP to increment the output to the next level. Thus, each time the host
computer issues a positive pulse, the BOP increments and the DVMs take measurements on
the trailing (negative-going) edge of the positive pulse. The positive pulse can be very short
(less than 2 microseconds) with this functionality.
3. The explanation below shows how each step of the list functions once the list is entered and
VOLT:MODE LIST (the last step) is executed.
list:cle Clears the list.
list:volt:apply level,.001,0 Establishes the list as a voltage list, output set to 0V.
list:dwell:points? Returns 10. (Wait of 33 milliseconds uses 10 points.)
list:wait:ledge 0 Maintains output at 0V, waits for Input trigger to have a high to low
edge before proceeding.
--- Host computer issues high pulse. Input Trigger goes low at trailing (negative-going) edge of
pulse from host commuter and List proceeds to next point. One millisecond after pulse issued,
DVM takes measurements.
list:dwell:points? Returns the current point location (3). (Used for list:repeat.)
list:repeat 9,10,1.1,2.2,3.3,4.4,5.5,6.6,7.7 Repeats step 9 and 10 (list:volt:apply lev and list:wait:ledge),
except each pair is set to the voltage specified in the array. This
adds 14 points to the list and sets the output values of each pair to
be 1.1V, 2.2V, 3.3V, 4.4V, 5.5V, 6.6V and 7.7V.
list:count 2 Implements the waveform through two loops of the data.
curr 5;:outp on Set output on, output current to 5A.
VOLT:MODE LIST Executes the above list. At each high-to-low transition of the Trigger
Port input, the BOP increases its output voltage in 1.1 volt incre-
ments. The duration of each increment is not controlled by the inter-
nal clock of the BOP, but instead by the high-to-low edge of the
pulse from the host computer.