HP VXI E1432A - Manual (Page 195)

General
Option AYF, Tachometer Input, provides two
tachometer inputs. When this option is installed, 2 of
the 3 SMB connectors on the VXI module are used for
tachometer inputs. When this option is not installed,
these connectorsare normally used for “External
Sample” and “Trigger.”
Each tachometer input has a programmable trigger
level. Each tach pulse causes a “Tach Edge Time” to be
recorded in a 16384-word FIFO. A “Tach Edge Time” is
the instantaneous value of the 32-bit “Tach Counter”.
A “Decimate” number can be set to ignore a number of
tach pulses before recording each Tach Edge Time. A
“Holdoff” time can be set to avoid false triggering due
to ringing.
One of the tachometer inputs can be programmed for
use as a trigger input rather than a tachometer input.
In this mode, the tachometer option can trigger the
system and measure the time between the trigger and
the next sample clock edge.
The analog signal from either of the Tachometer inputs
can be routed to an input channel using the internal
calibration path.
Tach Counter 32-bit counter with roll-over detector bit
Decimate Counter 16-bit counter
Input Signal Trigger Level (typical)
Voltage Range
Resolution, levels < ± 5V
Resolution, levels > ± 5V
Hysteresis
Slope
− 25 V to + 25 V
40 mV
200 mV
Programmable, 0 to 250 mV
Programmable, positive or negative
Input Signal Timing
Minimum pulse width
Maximum pulse rate
Trigger holdoff
5 µs
100 kHz
1 to 65536 clock periods
Input Impedance 20 kΩ (typical)
Option AYF Tachometer Input
Specifications
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