Hach-Lange Sigma SD900 Portable - Manual (Page 78)

76
Wiring for non-Sigma flow meters
C Pulse input Brown
This input triggers sample collection.
The signal may be generated by:
• An external flow meter or other
device with an appropriate control
output.
• Simple floating (dry) contact
closure.
The sampler is capable of accumulating
from 1 to 9,999 input pulses. This count
is advanced at the beginning (rising
edge) of the input signal. Each contact
closure output from a flow meter
represents a specific flow volume.
The contact closure signal is sent more
frequently for high flow rates, and less
frequently for low flow rates. The
sample frequency will increase as the
flow rate increases and decrease as the
flow rate decreases, thus taking
samples in proportion to flow rate.
This input responds to a positive pulse with respect
to Common (pin B). It is terminated (pulled low) to
Common (pin B) through a series 1 k
Ω resistor and
7.5 V zener diode.
Absolute maximum input: 0 to 15 VDC with respect
to Common (pin B). Signal required to activate input:
5–15 V positive going pulse with respect to common
(pin B) of at least 50 millisecond duration. Source
impedance of driving signal should be less than
5 k
Ω.
Dry contact (switch) closure of at least 50 millisecond
duration between pin A (12 VDC) and pin C (Pulse
Input). Contact resistance should be less than 5 k
Ω.
Contact current will be less than 8 mA DC.
D
Liquid level
actuator/aux
iliary control
input
Orange
This input sends a signal to the
microprocessor inside the sampler
causing it to "wake up" and begin or
resume its sampling program.
Applications for this input include:
A simple float level switch (dry contacts)
may be used to actuate the sampler
when liquid is present.
Start this sampler after another sampler
has finished its program.
Start the sampler in response to some
user-defined condition from an external
device that provides an appropriate
control signal. For example a pH meter
could be used to initiate sampling in
response to a high or low pH condition.
This input is terminated (pulled high) to an internal
+5 V supply through an 11 k
Ω resistance and
protected by a series 1 k Ω resistor and 7.5 V zener
diode terminated to Common (pin B). The input
responds to a high to low voltage transition with a
logic low pulse width of at least 50 milliseconds.
Absolute maximum input:
0 to 15 VDC with respect to Common (pin B). Signal
required to activate input:
External logic signal having 5-15 VDC power source.
The drive signal should be normally high. The
external driver should be capable of sinking 0.5 mA
@ 1 VDC maximum at the logic low level.
A logic high signal from a driver with power source of
greater than 7.5 V will source current into this input
at the rate of: I = (V - 7.5)/1000 where:
I is the source current
V is the power supply voltage of the driving logic.
Dry contact (switch) closure of at least 50 millisecond
duration between pin D and pin B (common).
Contact resistance should be less than 2 k
Ω. Contact
current will be less than 0.5 mA DC.
E
Special
output
Yellow
Normally at 0 VDC, this line goes to +12
VDC upon any of the selected events
described in
section 5.3.2 on page 52 .
This output is thermally protected against short
circuit currents to common (pin B). Limit external
load current to 0.2 A.
The output is normally logic low (0 VDC) with respect
to common (pin B). Active high output levels are:
15 VDC nominal when using AC power to power the
sampler
12 VDC nominal when using battery 8754400 to
power the sampler.
Table 8 Half-cable wiring information for non-Sigma flow meters (continued)
Pin
Signal
description Wire
color
1
Purpose Rating