Keithley 194 Instruction Manual page 44

OPERATION
3.4.6 Data Entry Examples
The examples below will help demonstrate the basic pro-
cedure for entering instrument data. The various operating
modes that are used here as a demonstration aid are
covered in more detail in subsequent paragraphs of this
section.
Example 1: Entering voltage units.
1. Press LEVEL to enter the trigger level entry mode. The
instrument will then display the presently pro-
grammed trigger level. For example, the display might
show:
o.,v
2. To key in a trigger level of -1.675V, press: +/-, 1, ., 6,
7, 5. The display will show the numbers as they are
keyed in.
3. Press V to store the new trigger level in memory. The
instrument will briefy display the new value and then
return to the previous operating mode.
Example 2: Entering frequency/time units.
1. Press the RATE key to enter the sampling rate entry
mode. The instrument will then display the presently
programmed value, for example:
166.7~
2. At this point, you can toggle between reciprocal time
and frequency units by pressing the FREQiTIME key.
3. Press FREQiTIME until time units are entered (for ex-
ample, Ins)
4. To key in an interval of 23.4msec, press: 2, 3, ., 4, ms.
5. Press RATE to get back into the rate entry mode.
6. Press the FREQiTIME key and note that you can toggle
the display between frequency and time units. With a
programmed interval of 23.4msec, the corresponding fre-
quency is 42.73504Hz.
Example 3: Demonstrating a NMBR TOO SMALL error.
1. Press RATE to enter the sampling rate entry mode.
2. Press FREQlTIME (if necessary) to display time inter-
val units.
3. To attempt to program a Oms (invalid) rate, press: 0, ms.
4.Note that the instrument displays the NMBR TOO
SMALL error message, and then returns to the previous-
ly programmed value.
Example 4: Demonstrating the use of the CANCEL key.
1. Press RATE to enter the sample entry mode. Note that
the instrument displays the presently programmed
value.
2. Press: 3, 5.
3. Press CANCEL, and note that the display returns to the
previous value.
4. press: 5, 0, ms; note that the last valrx is entered into
"W""KY.
Example 5: Using the cursor keys.
1. Press RATE to enter the sampling rate entry mode and
note that the presently programmed value is displayed.
2. Use the right cursor (Uprange) key to move the flashing
cursor to the right. You can stop on any digit and make
a change, if desired. If you move off the display to the
right, the cursor will wrap around to the first digit on
the left.
3. Using the left cursor (Downrange key), mow the
flashing display cursor to the left. Again, you can stop
on any digit and make a change, if necessary. Once the
cursor reaches the extreme left, it will wrap around to
the right most digit.
4. Once all changes have been made by using the cursor
keys, press ENTER to store the new parameter in
mem0*y.
3.5 RATE AND SAMPLES PROGRAMMING
A measurement sequence is made up of a number of iw
dividual samples taken at predetermined intervals.
Through the use of the RATE and SAMPLES keys, you
have precise control over how many samples to take, and
the time period between individual samples. I'rogram-
ming of each of these modes is performed by pressing the
appropriate key (RATE or SAMPLES) and then using the
data entry keys to enter the desired value. During the en-
try process, the display can be returned to the prwious
value by pressing the CANCEL key. If an incorrect
parameter is entered, the instrument will display an error
message (NMBR TOO SMALL or NMBR TOO LARGE,
as the case may be).
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