VXI VT1538A user manual Input and Output Characteristics

Figure 5. Recommended Connections and Voltage Limits

Input and Output Characteristics

This section describes the E1538’s channel input and output electrical characteristics. Refer to Figure 6 for the following discussions.

Input Characteristics When configured for input, E1538 channels provide digital input through the threshold comparator. The digital input threshold level is programmable with a SCPI command from -48 to +47.625 VDC in .375V steps (relative to the Lnn terminal). The threshold amplifier also provides typically 0.5 volts of hysteresis regardless of the threshold level setting. The input impedance in this configuration is greater than 100KΩ (as long as the 10KΩ pull-up resistor is OFF).

Channels 0 and 1 also provide the capability (when the VRS switch is ON) to read the output of variable reluctance sensors. Because the output of a VRS varies in relation to the velocity of the toothed wheel it is reading, the E1538A provides adaptive amplifiers for these channels. The function of the amplifier

Agilent E1538A Enhanced Frequency/Totalize/PWM SCP 9