3B45 / 3B46

Rev. 0 | Page 2 of 8

GENERAL DESCRIPTION

The 3B45 and 3B46 are single-channel isolated frequency input

moduels which produce simultaneous precision voltage and

current outputs proportional to input frequency. Model 3B45

accepts full-scale inputs ranging from 25 Hz to 1100 Hz, while

Model 3B46 accepts full-scale input from 520 Hz to 25kHz.

Both models enable the user to set the threshold to either 0 V

(for zero crossing signals) or +1.6 V (for positive level signals),

and the hysteresis to either 0 or +4 V. Hysteresis can be set for

any value within this range using the supplied AC1310 ranging

card. The 3B45 and 3B46 shield their computer side outputs

from damage and loss of signal integrity from field-side over-

voltage faults, withstanding up to 220 V rms at their input

terminals. The current output withstands 130 V rms without

damage and interfaces user equipment through screw terminal

connections. In addition, all 3B45 and 3B46 models are plug-in,

mix-and-match and hot-swappable, so each can be inserted or

removed from any socket in the same backplane without

disrupting system power.

3B Series Custom-Ranging Program – Externally-

programmable Model 3B45-00 and 3B46-00 enable the user to

configure a special input range by using the supplied plug-on

AC1310 ranging card, which houses user-supplied resistors to

determine hysteresis, zero and span. To facilitate selecting

resistors, a Windows program, 3B-CUSTOM, calculates resistor

values based on the user-desired input/output ranges.

The 3B45 and 3B46 compare the input signal to the user-

any wave shape that exceed the combined threshold and

determined by the input frequency. The comparator output is

then transmitted across a proprietary transformer-coupled

isolation barrier. A demodulator on the computer side of the

signal transformer recovers the original signal, which is then

filtered and buffered to provide a low-noise, low-impedance

output voltage; this output also drives a voltage-to-current (V/I)

converter to provide a simultaneous current output for

interfacing versatility.

Setting the threshold value is a simple matter of externally

wiring to the 3B Series backplane screw terminals. The

threshold for measuring a zero-crossing voltage waveform (such

as sine waves) can be set to 0 volts by connecting terminal 3 to

terminal 4. The threshold for a positive level signal (such as a

TTL or pulse train waveform) can be set at +1.6 V by

connecting terminals 1 and 2. Hysteresis for both input signal

types is set at 0 V, but can be changed to +4V by removing the

jumper that is installed on the AC1310 ranging card shipped

with each unit.

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Figure 2