Laurel Electronics LAUREATE SERIES 2 COUNTER-TIMER-SERIAL INPUT METER - Manual (Page 13)

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10. DUAL CHANNEL PULSE OR AC INPUT SIGNAL CONDITIONER
The dual channel signal conditioner board is used for the frequency, rate, period, timing,
batch control, phase and duty cycle meter functions. The board needs to be configured via
jumpers for the input signal type and level. It is recognized by the meter software, which will
bring up the applicable menu items. The dual channel pulse input signal conditioner does
not require calibration, since the quartz crystal oscillator used for frequency and timing
applications is located on the counter main board.
Note: Letters indicate
jumper position. Jumpers are
installed on pins adjacent to
letters.
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 meter will not operate properly. The larger the difference between
the high and low thresholds, the more immune the meter 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 meter from counting extra pulses due to contact bounce.
Function Block Jumper Setting
Frequency Response A0 & B0 -
b
a
1 MHz max
30 kHz max
250 Hz max
Bias Resistor A1 & B1 a
b
10 kOhm pull-up to 5V
10 kOhm pull-down to -5V
Contact Debounce A4 & B4 b
a, c
c
None
3 msec
50 msec