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SECTION 4 INPUTS
4-1 Digital Pulse Inputs (Terminal 3, 4)
Digital Pulse Inputs: The input board is a
separate board that is plugged into the mother
board just behind the display. All digital inputs
are on the same board. There are four dip
switches on the board. The input conditioning
characteristics may be altered by changing the
dip switches. A valid pulse is one which makes a
transition from the off state (low) to the on state
(high): a positive going edge. The off state is 0 - 1
VDC with respect to Terminal 12 (Ground). The
on state is 3 - 30 VDC with respect to Terminal
12. The input impedance is 10 K ohms. At 30
VDC, the current draw will be 3 mA. This should
be the maximum current that the KEPtrol F/C
will draw. Acceptable pulse width is determined
by the dip switch settings (See Table 4-1 below).
DIP SWITCH SETTINGS
SW1 SW2 SW3 SW4 Conditioning
ON
ON
---
---
0-40 Hz
min. 12.5 msec on/off
ON
OFF ---
---
0-400 Hz
min. 1.25 msec on/off
OFF OFF ---
---
0-9980 Hz
min. 50.1 usec on/off
---
---
OFF OFF
needs sourcing input
(drive input high).
---
---
OFF ON
needs sinking input
(pull input low).
↑
ON S1 S2 S3 S4
Table 4-1
3-5 Internal Operation
3-5.1 Digital Inputs and Computations
The 3-30 Volt input signal is filtered
electronically (See Section 4-1, Digital Pulse
Inputs).
Computations:
A Pulses In = A Count
A Count K Factor
B Pulses In = B Count
B Count K Factor
A Pulses In = A' Rate
A' Rate = A Rate
A Rate K Factor
Tau
B Pulses In = B' Rate
B' Rate = B Rate
B Rate K Factor
Tau
A+B Total
= A Count + B Count
(since last update)
A-B Total
= A Count - B Count
(since last update)
Net Rate
= A Rate - B Rate
(since last update)
If weighting is used:
Net rate
= (Old Rate x Weight) + New Rate
1
Tau = 1 sec or WINDOW if (Rate / 1 sec) = 0
(See Sections 1-3 and 3-3, Setting the
Ratemeter)
Preset Out
=
Count
≥
A Preset or
B Rate
≥
B Preset
or
Count
≥
B Preset or
Net Rate
≥
A Preset
or
A Rate
≥
A Preset or
Net Rate
≥
B Preset
Summary of Contents for KEPtrol F/C
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