Laurel Electronics LTM CTR SERIES PULSE, AC or PROCESS TOTALIZER INPUT, SERIAL DATA OUTPUT - Manual (Page 17)

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9. DUAL CHANNEL PULSE OR AC INPUT SIGNAL CONDITIONER BOARD
This signal conditioner board is used for the frequency, rate, period, timing, phase angle, or
duty cycle functions. The board needs to be configured via jumpers for the input signal type
and level. It is recognized by Instrument Setup software, which will bring up the applicable
menu items for the Input Option “Dual Sig Cond.” The board does not require calibration, since
the quartz crystal oscillator used for frequency and timing applications is located on the
transmitter main board.
Jumper Settings for Expected Signal Levels
The jumper settings for Channel A (A2 & A3) and Channel B (B2 & B3) need to be set for the
expected signal voltage. This voltage must be outside of the high and low thresholds per the
following table, or the transmitter will not operate properly. The larger the difference between
the high and low thresholds, the more immune the transmitter is to input signal noise.
Input must be Input must be Input must be A3
B3 A2
B2
below above
A3
B3 A2
B2
below above
A3
B3 A2
B2
below above
-
-
- a
b
-
-12 mV
-150 mV
-1.15V
+12 mV
+150 mV
+1.15V
a
a
a a
b
-
+30 mV
+350 mV
+1.25V
+60 mV
+600 mV
+2.1V
b
b
b a
b
-
-60 mV
-600 mV
-2.1V
-30 mV
-350 mV
-1.25V
Jumper Settings for Frequency Response, Bias Resistor, Debounce Time
Pull-up or pull-down resistors are used with open collector devices and dry contact closures
to provide input signal bias. They should not be connected for other inputs. Debounce
circuitry keeps the transmitter from counting extra pulses due to contact bounce.