VXI VT1538A user manual Rps

Figure 13. Sense Quadrature Position

Sense Rotational Velocity This means that the E1538 will read the rotational velocity of a toothed wheel sensor. The E1538 measures tooth-to-tooth period and converts it into units of revolutions per second (RPS). This function can only be linked to the E1538’s first channel. The function works for wheels that have either a missing, or an extra tooth to mark their index position. Figure 14 shows a wheel sensed with a variable reluctance sensor (using the VRS input option), but any wheel sensing method is applicable as long as it provides a digital output to the RVEL channel.

The value read by the algorithm can range from	1	RPS to	100, 000	RPS.
	nteeth		nteeth
	--------------		--------------------

As well as sensing rotational velocity, SENS:FUNC:RVEL provides the reference position to the SOUR:FUNC:RPULse function that generates angular positioned pulses. See page 30 for more information on RPULse.

To assign a channel to sense rotational velocity, use the command: [SENSe:]FUNCtion:RVELocity <n_teeth>,<index_type>,(@<ch_list>)

•<n_teeth> is the number of teeth that the wheel would have if it didn’t have missing or extra teeth. For example, we would set <n_teeth> to 12 for the wheel shown in Figure 14, even though with the missing tooth, there are only 11. <n_teeth> can range from 3 to 255.

22 Agilent E1538A Enhanced Frequency/Totalize/PWM SCP