MS-500 Mixed Signal Oscilloscope Option
12
ISSUED: June, 2009
MS-500-OM-E Rev C
DESCRIPTION OF OPERATION
The various components of the MS-500 Mixed Signal Oscilloscope Option acquire and store
digital data, trigger on digital patterns, interface the external module to the oscilloscope, and
provide a user-friendly interface for control and interpretation of data.
The MS-500 is an external device that digitally samples waveform data at up to 2 GS/s (for 500
MHz digital signals). Unlike a logic analyzer, it operates only in a Timing Analysis mode, so it
requires 4x oversampling to determine the correct digital edge position, and does not require the
user to input a clock.
While in SINGLE, NORMAL, or AUTO trigger mode, the MS-500 repeatedly samples each digital
channel’s voltage level. If the voltage is greater than the threshold voltage, the MS-500 stores a
1
in internal memory. Otherwise, a
0
is stored.
1
Threshold level
1 1 1 1 1 0 0 0 0 1 1 1 1 1 0 0 0 0 0
The minimum high voltage level is user definable by the hysteresis control up to 1.4 V above the
threshold. The maximum low voltage level is user definable by the hysteresis control up to 1.4 V
below the threshold. The minimum signal swing is 100 mV. The
indeterminate range
of 50 mV
around the threshold voltage level is the level below which the MS-500 will not operate. However,
the MS-500
can
support a signal as low as 100 mV only
if the input signal’s quality is adequate.
The MS-500 keeps sampling its inputs until the oscilloscope is put into STOP trigger mode. Data
is stored in a 50 Mpt internal memory that is periodically transferred to the oscilloscope via the
USB2.0 cable. If the oscilloscope is triggering in SINGLE or NORMAL trigger mode, data is
acquired and transferred only when the trigger condition is satisfied. The captured data is then
displayed on the oscilloscope grid in a time-aligned fashion.
In any trigger mode (AUTO, NORMAL, SINGLE), pressing STOP trigger cancels the acquisition,
which leaves the previously acquired data unchanged.
The MS-500 both samples incoming data and searches for trigger conditions.
The USB2.0 cable provides downloading of trigger conditions from the oscilloscope to the MS-
500 and uploading of digital data from the MS-500 to the oscilloscope.
