Hach 900 MAX - Manual (Page 34)

Page 32
Auxiliary Receptacle Pin Identification
8990hrd.fm
Section 2
Important: Whenever electricity is present, there is a possibility of electrical
shock. Before connecting the sampler to an ac power source, the following
safety precautions should be taken:
• Check the power source to make sure that it satisfies the ac power
requirements of the sampler.
• Make sure that all electrical installations and connections are in
accordance with national and local electrical codes.
• Before performing any maintenance, disconnect the sampler from the
power source.
• Do not attempt to make any connection or otherwise handle the electrical
components of the sampler when connected to ac line power if the
immediate area is wet, or if hands or clothing are wet.
• If the circuit breaker or fuse in the ac power source is tripped, determine
the cause before restoring power to the sampler.
• Make sure the power circuit is grounded and protected with a Ground
Fault Interrupter (GFI).
2.9 Auxiliary Receptacle Pin Identification
Pin A/White (12 V dc) Powers an external device or flow meter. Must be used in conjunction with Pin B (ground).
Pin B/Blue (Ground) Connected to dc ground and is isolated from the earth ground found in the ac power line.
Pin C/Yellow (Pulse Input)
With the sampler in Flow Proportional mode and connected to an external flow meter, a 5 to
12 V dc input pulse lasting at least 25 milliseconds will cause the sampler to decrement one
count. The 12 V dc line found on Pin A can be used directly with a simple contact closure to
Pin C or an external 5 to 12 V dc pulse may be applied providing the ground side of the
external signal is connected to the sampler ground at Pin B. This count is actuated at the
beginning of the input signal (the leading edge of the pulse).
Pin D/Black
(Liquid Level Actuator/
Auxiliary Control Input)
This line is held at 5 V dc inside the sampler. When shorted to ground (Pin B), a signal is sent
to the microprocessor inside the sampler causing it to “wake up” and begin or resume its
sampling program. It can be used in conjunction with a simple level float to actuate the
sampler when liquid is present or to take over after a second sampler has finished its
program. It may also be used with any device (such as a pH meter) that produces a dry
contact output to control the sampler in response to some user-defined condition (i.e. high or
low pH); must be used in conjunction with Pin B.
Pin E/Red (Special Output) Normally at 0 V dc, this line goes to 12 V dc upon any of the selected events described in.
Pin F/Green
(Program Complete Output)
Normally an open circuit, this line switches to ground for 90 seconds at the conclusion of the
sampling program. Used to “wake up” another sampler to take over sampling or to signal an
operator or data logger upon the completion of the sampling program. This pin is also used to
signal the bottle full condition in a single bottle/continuous mode, and will transmit the bottle #
to an 950 Flow Meter if the program complete signal is disabled.