Operator`s manual
21 Signametrics
2.10.5 Totalizer
• Active edge polarity: Positive or negative transition
• Maximum count: 10^9
•
Allowed rate: 1 to 30,000 events per second
•
Uses Threshold DAC
2.11 Trigger Functions
2.11.1 External Hardware Trigger (at DIN-7 connector)
Trigger Input voltage level range +3 V to +15 V activates the trigger.
Trigger Pulse Width
Minimum = 1/Aperture + 50µS
Minimum trigger input current 1 mA
Internal Reading Buffer Circular; 80 or 120 readings depending on resolution.
Isolation of trigger input ±50 V from analog DMM inputs, and from chassis
earth ground.
2.11.2 Analog Threshold Trigger
• Trigger point: Selectable positive or negative transition of set threshold.
• Buffer type: Circular
• Captures up to 120 post-trigger readings for apertures
< 625uSec.
• Captures up to 80 post-trigger readings for apertures > 625uSec.
•
Aperture range: 160ms to 625
µS (to 2.5µS with SM2064)
•
Read Interval
range
: 1/Aperture to 65ms
• User selects number of post-trigger readings.
• The number of pre-trigger readings: buffer size – post-trigger count.
• The number of cycles the circular filled, and the trigger point are retrievable.
2.11.3 Delayed Hardware Trigger
This function allows time for the signal to settle after a trigger has occurred.
It allows readings to be delayed up to 65mSec with 1
µSec resolution
.
It allows readings to be delayed up to 1s with 2
µs resolutions.
2.12 Measurement Aperture and Read Interval
Both Aperture and The Read Interval may be set. The range of values depend on the DMM model and its
mode of operation. For example, when using the internal buffer such as in External Trigger mode, the
Read Interval can be set smaller than in Command/Response operation. The time involved in processing
the measurement command and the post processing and transmission of the measurement results
constitute an overhead, which limits the minimum Read Interval to a value that is greater than the
Aperture. Setting it to zero (default) results in the fastest measurement rates at the selected Aperture. The
faster SM2064 has lower overhead and therefore a shorter minimum Read Interval than the SM2060. For
instance, with Aperture set to 625us and Read Interval set to zero, in command/response operation the
SM2060 measurement rate is about 1,090/s while that of the SM2064 is 1,370/s. This indicates overhead
of about 300µs for the SM2060 and 100µs for the SM2064.
The SM2064 has 31 A/D apertures available, ranging from 5 Seconds to 2.5µS
. The following table contains all
available measurement apertures and the corresponding minimum read intervals and measurement rates.
Power Line Rejection Command/Response
mode min. Read
H/W Trigger mode min. Read
Interval
(
s
)
/ max meas. Rate