Keithley 220 Instruction Manual page 19

In the step program mode the user can manually step through
the programmed memory locations one at a time. Each time it
is desired to advance to the next programmed memory loca-
tion the user presses the START/STOP button. The START/
STOP LED turns on for the duration of the programmed dwell
time. When the last programmed memory location is selected
fmemory location 5 in this example) pressing the START/
STOP button reverts the instrument to memory location 1.
In the single program mode the Model 220 cycles through all
the programmed memory locations one time. To start the
single program mode press the START/STOP button. Once
the single program mode is activated, the Model 220 starts
from the present memory location and advances to each pro-
grammed memory location. The instrument remains at each
memory location for the programmed dwell time and then ad-
vances to the next programmed memory location. After the
dwell time of the last programmed location the START/STOP
LED turns off and the single program mode is ended. The
Model 220 remains at the last programmed location until
power is turned off, RESET is pressed, memory location is
changed or the single or continuous program modes are ac-
tivated.
NOTE
An entry of zero for the dwell time for any
memory location is interpreted as a reset in the
step, single and continuous program modes.
In the continuous program mode the Model 220 cycles
through all the programmed mernor~ locations continuously.
To start the continuous program mode press the START/
STOP button. To stop the continuous program mode press the
START/STOP button a second time. When the START/
STOP button is pressed the second time the continuous pro-
gram mode is stopped at the present memory location. Once
the continuous program mode is activated, the Model 220
starts from the present memory location and advances to the
next memory location. The instrument remains at the present
memory location for the programmed dwell time (dwell time
can vary for each memory location) and then advances to the
next memory location. The cycle continues up to and including
the last programmed memory location and then reverts to
memarY location 1. At this point the cycle starts over again and
keeps repeating until the START/STOP button is pressed,
power to the instrument is turned off or the single or step prs
gram modes are selected.
Example 5-In this example the COPY button will be used to
duplicate the data of memory location 1 into memory locations
2, 3, 4 and 5. The COPY button function, when used in the
memory display mode, duplicates the source, V-limit, and
dwell time data of one memory location, into the next memory
location. Program the following parameters into memory loca-
tion 1 and use the procedure to duplicate these parameters into
memory locations 2, 3, 4 and 5.
Required Parameters:
1. 10.05mA Source
2. 25V V-limit
3. 525msec Dwell Time
1. Press MEMORY, 1, ENTER. (Selects memory location 1.1
2. Press SOURCE, 1. 0. ., 0, 5, EXPONENT, 3, ENTER. (Pro-
grams memory location 1 source for 10.05mA.I
3. Press V-LIMIT, 2, 5, ENTER. (Programs memory location 1
V-limit for 25V.j
4. Press DWELL TIME, 5. 2, 5, EXPONENT, 3, ENTER. (Pro-
grams marnon/ location 1 dwell time for 525msec.j
5. Press MEMORY, COPY, COPY, COY, COPY.
The parameters specified were programmed into the Model
220 by steps 1 through 4. The parameters of memory location
1 were duplicated into metnon/ locations 2, 3, 4 and 5 by step
5. To verify that the data was duplicated into the other memory
locations select each memon/ location and select each para-
meter for each memory location. For example: To verii that
10.05mA was duplicated into memon/ location 3 use the
following two steps.
1. Press MEMORY, 3. ENTER. (Selects memory location 3.)
2. Press SOURCE. (Displays memory location 3 source data.)
Example 6 Fabricating Output Waveforms-The Model
220 is capable of fabricating output waveforms. With the 100
memory locations the Model 220 can fabricate waveforms
with up to 100 individual steps. The following procedure is an
example of programming the Model 220 to output a square
wave of 1OmA to 2mA at 100Hz.
Required Output: 1OmA to 2mA square wave at 1OOHz with a
V-limit of 1OV.
NOTE
Cycle power to the instrument before starting this
example to avoid confusion of previously pro-
grammed memory locations.
1. Press MEMORY, 1, ENTER. (Selects memory location 1,)
2. Press SOURCE, 1, 0, EXPONENT, 3, ENTER. (Programs
memon/ location l's V-limit for lOV.1
3. Press V-LIMIT, 1, 0, ENTER. fPrograms memory location
l's V-limit for 1OV.)
4. Press DWELL TIME, 5. EXPONENT, 3, ENTER. (Programs
memory locetion 1 dwell time for 5msec.)
5. Press MEMORY, 2, ENTER. ISelects memory location 2.)
6. Press SOURCE, 2, EXPONENT, 3, ENTER. (Programs
memory location 2 source for 2mAj.b
7. Press V-LIMIT, 1, 0, ENTER. (Programs memory location 2
V-limit for 1OV.)
6. Press DWELL TIME, 5. + I-, EXPONENT, 3, ENTER. (Pro-
grams memory location 2 dwell time for 5msec.j
9. Press CONTINUOUS, OPERATE, START/STOP.
Upon completion of step 9 the Model 220 outputs a 1OmA to
2mA 1OOHr square wave as shown in Figure 2.4.
NOTE
When fabricating output wavefons ObseNe the
response time specifications of the Model 220.
Also, consider the affect of load imoedance on
the waveform to be fabricated.
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