Operator`s manual

Signametrics 44
) function, when making a measurement the DMM uses a default voltage of 0.45Vpk,
hich means that a sine wave that has a peak-to-peak amplitude of 0.9V. This level is used during both, open
t uctors
t t this default value. The stimulus voltage can be set from
to 5V peak using the DMMSetACCapsLevel() function. Any time the stimulus level is adjusted; open
alibration must be carried out. The results of DMMOpenCalACCaps() are kept in memory until the DLL is
t in improved accuracy. AC Capacitance measurement
Aperture of at least 80ms.
.11 Inductance Measurement (SM2064)
The ecision AC source with a frequency range of 20 Hz to 75 kHz. Since
to
Relative’ function with
fter Op measures and
ent (SM2064)
capacitance C (with the end of the
th the end of the cable shorted). The cable’s impedance equals the square
/C. Be certain the cable is long enough such that both the capacitance and inductance are within the
pec
e at pins 7 (+) and 4 (-) of the
IN-7 connector. The External Trigger operation may be aborted using the DMMDisarmTrigger(). Read about
e PC chassis
r DMM terminal. Do not apply any voltages greater than 35 V to the DIN connector pins.
g this limit may result in personal injury and/or permanent damage to the DMM.
plugged into the DMM, with the other end open. See figure 4-12 above for connection. If not modified by the
DMMSetACCapsLevel(
w
calibration and measurements. Since the DMM is op imized for this value, and it is well below most semicond
on voltage, it is recommended no o change the level from
0.1V peak
c
unloaded. Repeating Open calibration periodically will resul
function must be used with a DMM
4
SM2064 measures inductance using a pr
inductors can vary greatly with frequency, you should choose the appropriate generator frequency. In addition
inductance, the inductor’s Q factor can be measured. A high quality coaxial or at least a shielded cable is highly
recommended. For best accuracy, perform the Open Terminal Calibration function within an hour of inductance
measurements. The Open Terminal Calibration function must be performed with the cable or probes plugged into
the DMM, but with the other end open circuited. This process characterizes the internal signal path inside the
DMM, the open application cable and the DMM circuitry. Set the Aperture to 40ms or to higher values for better
accuracy.
or best measurement accuracy at low inductance values, zero the DMM often by using the ‘
F
the leads shorted. This must be done a en Terminal Calibration operation. This Relative action
MM ble.
removes the inductance of the D signal path and that of the application ca
4.12 Characteristic Impedance Measurem
racteristic impedance, measure the cable’sTo measure transmission line’s cha
n) and then its inductance L (wi
cable ope
oot of L
r
s
ified measurement range of the SM2064.
4.13 Trigger Operation
Several trigger functions are provided; some are by means of an input signal to the trigger input, and
others by means of input level.
The Trigger functions provide for a stand-alone capture of measurements. The
on-board controller supervises the operation, and when conditions are valid, it captures data into its circular buffer,
or sends it back to the PC bus. The aperture must be set to a value equal or smaller to 160ms for all trigger
operations.
4.13.1 External Hardware Trigger
The External Hardware Trigger inputs are isolated high and low input lines availabl
D
these functions in the Windows Command Language section (5.6) for details.
Warning! The DIN connector pins are only protected to a maximum of 35 V with respect to th
or any othe
Violatin
4.13.1.1 Edge Triggered Operation
In this mode of operation, the DMM takes between 1 and 120 (or 1 and 80 if high resolution)
measurements in response to the currently set edge. Once armed, the DMM waits for this Trigger event
until it occurs, or the process is aborted (DMMDisarmTrigr(nDmm)). While waiting for the selected
trigg
er edge, the DMM continuously makes measurements and stored them to the internal buffer, utilizing
of
trigger occurred before the buffer
the whole buffer. Depending on the length of time prior to the trigger event, this circular buffer may or
may not be filled / over-written. For additional information a counter is provided to counts the number
times the buffer fills up while waiting for the trigger event. On reception of the trigger, the DMM takes
the number of readings specified in the DMMArmTrigger(nDmm, n) command and indicates it is ready
(DMMReady() = TRUE). These post trigger readings are stored in subsequent locations of the circular
buffer. At the end of the capture process the internal buffer pointer points to the beginning of the buffer.
Following the completion of the process, subsequent readings from the buffer will return 120-n pre-
trigger readings, followed by n post trigger readings. In the case where