BOP-1K 111315 B-19FIGURE B-6. USING LIST:WAIT COMMANDS TO CONTROL GENERATION OF A WAVEFORM MEASURED BYMULTIPLE EXTERNAL DEVICES USING A SINGLE EXTERNAL PULSENOTES: 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 controlpulse. This example assumes BOP and a number of switching DVMs are connected to a UnitUnder Test (UUT). The DVMs are programmed to wait 1 mS after a high pulse is received from thehost computer, then take a few measurements. The same high pulse 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 incre-ment the output to the next level. Thus, each time the host computer issues a positive pulse, theBOP increments and the DVMs take measurements on the trailing (negative-going) edge of thepositive pulse. The positive pulse must be greater than 4 mS in width for this example to operatecorrectly.3. The explanation below shows how each step of the list functions once the list is entered andVOLT: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. (Levels below 3 mS use 10 points.)LIST:WAIT:HIGH 0 Maintains output at 0V, waits for Input trigger high before proceeding.--- Host computer issues high pulse. Trigger input goes high and List proceeds to next point.LIST:WAIT:LOW 0 Maintains output at 0V, waits for Input Trigger low before proceeding.--- Input Trigger goes low at trailing (negative-going) edge of pulse from host commuter and Listproceeds to next point. One mS after pulse issued, DVM takes measurements.LIST:WAIT:HIGH 1.1 Sets output to 1.1V (next point in waveform), waits for Input Trigger highbefore proceeding.--- Host computer issues another high pulse. Trigger input goes high and List proceeds to nextpoint.LIST:WAIT:LOW 1.1 Maintains output at 1.1V, waits for Input Trigger low before proceeding.--- Input Trigger goes low at trailing (negative-going) edge of pulse from host computer and Listproceeds to next point. One mS after pulse issued, DVM takes measurements.LIST:DWELL:POINTS? Returns the current point location (6). (Used for list:repeat.)LIST:WAIT:HIGH 2.2. Sets output to 2.2V (next point in waveform), waits for Input Trigger highbefore proceeding.--- Host computer issues another high pulse. Trigger input goes high and List proceeds to nextpoint.LIST:WAIT:LOW 2.2 Maintains output at 2.2V, waits for Input Trigger low before proceeding.--- Input Trigger goes low at trailing (negative-going) edge of pulse from host computer and Listproceeds to next point. One mS after pulse issued, DVM takes measurements.LIST:DWELL:POINTS? Returns the current point location (16).LIST:REPEAT 6,7,3.3,4.4,5.5,6.6,7.7 Repeats step 6 and 7 (list:wait:high and list:wait:low), except each pair isset to the voltage specified in the array. This adds 10 points to the list andsets the output values of each pair to be 3.3V, 4.4V, 5.5V, 6.6V, 7.7V.LIST:COUNT 2 Implements the waveform through two loops of the data.LIST:DWELL:POINTS? Returns 10.LIST:COUNT:SKIP 10 Bypass the first step in the repeated points.CURR 5;:OUTP ON Set output on, output current to 5A.--- Ensure Input Trigger is low.VOLT:MODE LIST Executes the above list. At each low transition of the trigger line the BOPincreases its output voltage in 1.1 volt increments. The time period foreach increment is controlled not by the internal clock of the BOP butrather the high-to-low edge of the pulse from the host computer. The useof LIST:WAIT:HIGH followed by LIST:WAIT:LOW ensures the BOP waitsfor a high-to-low edge transition on the trigger input before increasing theoutput.
