GE AT868 AquaTransrmUltrasonic Flow Transmitter

GE AT868 AquaTransrmUltrasonic Flow Transmitter

To ensure safe and reliable operation of the Model AT868 Flowmeter,
the system must be installed and programmed in accordance with the
guidelines established by GE Infrastructure Sensing engineers. Those
guidelines, explained in detail in this chapter, include the following
topics:
• Unpacking the Model AT868 system
• Selecting suitable sites for the electronics enclosure and the
flowcell/transducers
• Installing the flowcell/transducers

The Model AT868 may be ordered for operation with power inputs of
85-265 VAC or 12-28 VDC. The label on the side of the electronics
enclosure lists the meter’s required line voltage and power rating. The
fuse size is listed on label located under the fuse. Be sure to connect
the meter only to the specified line voltage.

Wiring Std 0/4-20 mA
Analog Outputs

The Model AT868 flow transmitter has one isolated 0/4-20 mA
analog output per channel (designated as Output A and C). These
outputs can be configured independently. Typically, Output A is used
for Channel 1 and Output C is used for Channel 2; however, analog
outputs can be configured to measure either channel.

Connections to this output may be made with standard twisted-pair
wiring, but the current loop impedance for these circuits must not
exceed 600 ohms.
To wire the analog outputs, complete the following steps:
1. Follow the instructions on page 1-4 to prepare the unit before you
connect power.
2. Refer to Figure 1-4 on page 1-14 for the locations of the
appropriate terminal blocks and wire the analog outputs as shown.
Secure the cable clamp.

3. Do one of the following:
• Proceed to the next section to continue wiring the Model AT868
flow transmitter.
• Reinstall the plastic shroud, replace the front cover on the
enclosure and tighten the screws.

Wiring the Totalizer/
Frequency Output

The Model AT868 also provides a second output per channel
(designated as Output B and D) that can be configured as a totalizer
or frequency output using the Instrument Data Manager (IDM)
software.
Like the analog outputs, these outputs can also be configured
independently. Typically, Output B is used for Channel 1 and
Output D is used for Channel 2; however, outputs can be configured
to measure either channel.

To wire the totalizer/frequency outputs, complete the following steps:
1. Follow the instructions on page 1-4 to prepare the unit before you
connect power.
2. Refer to Figure 1-4 on page 1-14 for the location of the
appropriate terminal blocks and wire the totalizer/frequency
outputs as shown. Secure the cable clamp.

3. Do one of the following:
• Proceed to the next section to continue wiring the Model AT868
flow transmitter.
• Reinstall the plastic shroud, replace the front cover on the
enclosure and tighten the screws.

Wiring an RS232 Interface

Use the serial port to connect the Model AT868 flow transmitter to a
printer, an ANSI terminal or a personal computer. The RS232
interface is wired as Data Terminal Equipment (DTE), and the signals
available at the COMMUNICATION terminal block are shown in
Table 1-1 below.
1. Follow the instructions on page 1-4 to prepare the unit before you
connect power.
2. Use the information in Table 1-1 below to construct a suitable
cable for connecting the Model AT868 to the external device. If
desired, an appropriate cable may be purchased from the factory.

Wiring an RS485 Interface

Use the optional RS485 serial port to network multiple AT868 flow
transmitters to a single computer terminal. Upon request, the standard
RS232 port on the AT868 may be configured as a two-wire, halfduplex
RS485 interface, through a device such as the INMAC Model
800052 RS232-RS422/RS485 converter.
If the AT868 is configured at the factory for RS485 operation, the
INMAC converter is not necessary.