Tabor 8020, User Manual

Page: 29 / 111

NOTE
Software reset has no effect on stored front
panel set-ups in memory locations 00
through 30. Software reset also has no effect
on the programmed GPIB address.
3-6. DISPLAY MESSAGES
Model 8020 has several display messages pertaining to
its operation. The generator also displays an error indi-
cation when a front panel programming error is detected.
These messages and error indications are discussed in
the following. Note that the instrument has a number of
additional display messages associated with IEEE-488
programming. These messages are discussed in section
4 of this manual.
3-7. DETECTING PROGRAMMING ERRORS
Model 8020 is a product of many years of experience and
complete understanding of human engineering require-
ments. During its design stage, a great deal of time was
devoted for simplifying front panel programming proce-
dures, thereby minimizing the potential of programming
errors. It is impossible however for an inexperienced op-
erator to completely avoid some errors. For such cases,
the function generator employs a built-in error detection
mechanism which warns against programming errors.
Errors are categorized in four main groups:
1. General errors
2. Pulse/Ramp setup errors
3. Offset errors
4. IEEE errors
3-7-1. General Errors
Errors in this group are caused by improper usage of the
instrument. Such errors occur while attempting to place
the instrument in an illegal mode. For example, depress-
ing simultaneously two push-buttons (except [P.SET])
has no valid definition. In this case, the instrument sim-
ply ignores this error and continues with its normal op-
eration.
3-7-2. Pulse/Ramp Set-up Errors (model 8021 only)
The pulse/ramp setup errors are inter-parameter incon-
sistencies errors, such as pule width greater than the se-
lected period. The pulse generator tests the programmed
parameter every time that a modifier push-button is de-
pressed. Programming the Model 8020 with pulse/ramp
errors is possible and executable however, when such er-
rors are detected, the light next to the selected waveform
starts blinking; indicating that the signal at the output
connector may emerge with other parameters then those
programmed. The light blinks until the error conditions
are removed.
Pulse/Ramp errors may occur under one or more of the
following conditions:
1. The programmed pulse/ramp WID (width) parame-
ter is greater than the selected period (1/FREQ).
2. Model 8021 is placed in sweep mode and the pro-
grammed pulse/ramp width parameter is greater than the
selected sweep stop period.
3. Model 8021 is placed in internal triggered mode and
the programmed pulse/ramp width is greater than the se-
lected internal trigger period.
4. The programmed ramp width is outside the limit of
5.00 uS.
5. The programmed ramp frequency is outside the limit
of 150 KHz.
3-7-3. Offset Errors
Normally, the output waveform is used symmetrically
around the 0 V line. This means that with an output volt-
age of 10 Vp-p and with no offset applied, the lowest
peak reaches -5 V. Consequently, the highest peak
r5 V. The instrument provides an additional
flexibility by using its output waveform in conjunction
wth an offset voltage. It is however, impossible to exceed
the instrument limits. Offset and amplitude are inde-
pendently selectable within the limits given in Table 3-2.
The instrument will reject any attempt to call the
[OFST] function if the sum of the amplitude and the offset
exceeds the specified limits and will display the following
error message on its read-out:
ERR
The function generator then resumes normal operation.
No offset is applied to the output waveform.
Operating Instructions Model 8020
Page 3-6