Hach Accu4 User Manual page 15

Connect the TTL input (optional)
W A R N I N G
Potential Electrocution Hazard. Always disconnect power to the
instrument when making electrical connections.
The controller has one TTL input that lets the user hold or transfer the
analog outputs and the relays. Refer to
input feature function is the same as the output state (HOLD, XFER or
ACTIVE) selected during the last calibration.
• HOLD—The analog outputs and relays are held at their present
values/on-off states.
• XFER (transfer)—The analog output values and relay states are
changed to the selected Set Transfer values/states. Refer to
Configure the analog outputs
on page 19.
• ACTIVE—The analog outputs and relays represent the measured
turbidity. The TTL input is disabled.
To apply a TTL hold or transfer, locally or remotely connect the two TTL
terminals. When this connection is broken, the applied hold or transfer
releases.
Note: The TTL input feature is disabled during calibration and system diagnostic
tests that are started by the user.
Plumbing
Plumb the sensor
D A N G E R
Fire hazard. This product is not designed for use with flammable
liquids.
N O T I C E
When metal fittings are used, do not over tighten them onto the plastic inlet or
outlet fitting of the sensor or damage to the plastic fitting may occur.
Figure 5 on page 10. The TTL
on page 19 and Configure the relays
Install the sensor in an "in line" process configuration using a closed loop
piping arrangement or in a sample bypass line configuration using an
open drain piping arrangement. Refer to
Procedure notes:
• Bushings may be used to decrease to a smaller tubing size. Barb or
tube fittings may be installed.
• Use larger sample tubing for applications in which sediment buildup
commonly occurs. A faster flow rate helps flush sediment through the
sensor.
• Use Teflon tape to seal the inlet and outlet connections. Do not use
pipe dope or other liquid sealants.
Figure 9 and Figure 10.
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