6F8A0917
-
149
-
11. Communications Function
The LF232 Series Converters are equipped with HART*1 protocol to transmit digital signals over the 4
to 20mA output line. The AF900 hand-held terminal (hereafter called HHT) can be used to check or
change various parameters, calibrate the flowmeter or monitor the measured value from a remote
place.
For the detailed operation and specification of HHT, refer to the "Hand-held Terminal for Sensor with
Communication Function AF900 Instruction Manual" (6F8A0849).
*1 HART protocol: The “HART protocol”, which stands for Highway Addressable Remote
Transducer, is the name of the communication protocol for industry sensors that is
recommended by HCF (HART Communication Foundation).

11.1 Connection with the HHT terminal

Connect the probe cable of the HHT terminal in parallel with the load resistor which is wired from the
current output terminals (+ and ) of the flowmeter. Since the tip end of the probe cable is a pair of
clips, use a junction terminal or a terminal block, etc. to connect with the clips of the probe. To
connect the HHT directly to the flowmeter, use the terminals + and of the converter main unit
terminal block. Though the current output terminal has polarity, the HHT connection cable has no
polarity.
See Figure 11.1 and 11.2 for connection examples.
4 to 20 mADC
HHT
LF232 Converter
(Communication line)
Load resistor
Terminal block or
junction terminal
Figure 11.1 Connections to the Current Output Line