HP VXI E1432A 8 of, Specifications, Option AYF Tachometer Input

Option AYF Tachometer Input

Specifications

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	− 25 V to + 25 V
Resolution, levels < ± 5V	40 mV
Resolution, levels > ± 5V	200 mV
Hysteresis	Programmable, 0 to 250 mV
Slope	Programmable, positive or negative
Input Signal Timing
Minimum pulse width	5 ∝s
Maximum pulse rate	100 kHz
Trigger holdoff	1 to 65536 clock periods
Input Impedance	20 kΩ (typical)

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