Choosing The Dial Method (Tone Or Pulse); Analog Communications; Ma Output; Ma Connections - Hach Sigma 950 Instrument Manual

Communications Setup

8.2.3.4 Choosing the Dial Method (Tone or Pulse)

8.3 Analog Communications

8.3.1 4–20 mA Output
8.3.1.1 4–20 mA Connections
64
Press the
CHANGE CHOICE
the center of the display. Press the
11:00 AM 21 - APR - 01
ACCEPT
CANCEL
Channels 1 through 7 are analog input channels that can accept a signal from an external
device. This signal may range from -4 V dc (min.) to +4 V dc (max.) or from 0 to 20 mA dc
depending on the input selected. In some cases, input signals from certain devices may
also fall somewhere within those ranges. For that reason, each analog input channel
must be mapped to the minimum and maximum signal limits of the external device.
Note: Due to the power demand of current loops, this option requires that an ac power supply be
installed on the flow meter. Battery power is not sufficient to support the
4–20 mA current loop power requirements.
The 4–20 mA option is available as one or two current-loop interfaces for controlling
external devices such as a chlorinator or a chart recorder. Either one or both of the 4–20
mA outputs can be factory installed and are isolated from each other.
Isolation Voltage Rating
Note: 950 flow meters are available with one or two 4–20 mA outputs. Both outputs are installed in
one receptacle.
• Between flow meter and either 4–20 mA output: 2500 V ac
• Between the two 4–20 mA outputs: 1500 V ac
• Maximum Resistive Load: 600 ohms
• Output Voltage: 24 V dc, no load
Pin
A
B
C
D
Cable Required:
4–20 mA Output Cable Assembly, 25 ft (7.6 m), 4-pin connector on one end, tinned wire
leads on the other end (P/N 2924).
soft key until the correct dial method (pulse/tone) appears in
soft key to continue.
ACCEPT
DIAL METHOD
TONE
CHOICES: TONE, PULSE
Table 25 4–20 mA Connector Pin Assignments
Signal Description
output A + (pos)
output A - (neg)
output B + (pos)
output B - (neg)
MODEM SETUP
CHANGE
CHOICE
Wire Color
yellow
black
red
green