Hach 900 MAX, Instrument Manual

Page: 89 / 160

Section 6
Page 87
8990cm.fm
4–20 mA Option
6.3 4–20 mA Option
The 4–20 mA option provides a current loop for controlling external devices
such as a chart recorder or PC. Either one or both of the 4–20 mA outputs can
be factory installed and are isolated from each other.
6.3.1 4–20 mA Connection
The interface has a 3-ft cable with a connector on one end, and a 10-ft cable
with two open wire leads on the other. Insert the connector into the sampler
receptacle labeled “Auxiliary”, located on the left side of the control housing.
On the 10-ft cable, the wire with clear insulation is positive (+) and the wire
with black insulation is negative (-).
Rating:
•
Isolation Voltage:
Between sampler and either 4–20 mA output: 2500 V ac
Between the two 4–20 mA outputs: 1500 V ac
• Maximum Resistive Load: 600 ohm
• Output Voltage: 24 V dc - no load
Cable Required
4–20 mA Interface Cable (Cat. No. 2924), 25 ft long, 4-pin connector on one
end, tinned wire leads on the other end.
6.3.2 4–20 mA Programming
1. From the Main Menu, select
OPTIONS > ADVANCED OPTIONS > 4–20 mA
OUTPUTS > SELECT
.
Note: When the 4–20 mA outputs
are disabled and not completely
turned off, they will continue to
output a steady 4 mA.
2. Enable the 4–20 mA outputs by pressing
CHANGE CHOICE
while in the
4–20 mA output menu.
3. When the display shows the outputs as enabled, press
ACCEPT
.
4. Choose either OUTPUT A or OUTPUT B. Use the
UP
and
DOWN
keys to
highlight the choice, then press
SELECT.
Table 16 4–20 mA Connections (J18)
Pin Signal Description Wire Color
A Output 1 + (pos) Yellow
B Output 1 - (neg) Black
C Output 2 + (pos) Red
D Output 2 - (neg) Green
11:00 AM 21 - APR - 01 4–20 mA OUTPUTS
SELECT
OUTPUT A
OUTPUT B
RETURN