Communications Function; Connections With Hht Terminal - Toshiba LF620 Instruction Manual

11. Communications Function

The LF62* Series Electromagnetic Flowmeter uses the HART*1 protocol to transmit digital signals
over the 4-20mA output line. The AF900 hand-held terminal is used to communicate with the LF62*
using the HART protocol. Through remote operation, you can check or change the various parameters,
calibrate the flowmeter or monitor the measurement value.
For detailed operation and specifications of HHT, refer to the instruction manual of the AF900
hand-held terminal for sensor with communication function.
*1 HART protocol:
HART, Highway Addressable Remote Transducer, is a communication protocol for industrial
sensors recommended by HCF (HART Communication Foundation).
By adding an optional PROFIBUS or Modbus communication board to the converter, the converter can
be used as a PROFIBUS-PA or Modbus slave device to communicate digital data with PROFIBUS or
Modbus master device .
For details of PROFIBUS or Modbus communication, refer to the instruction manual of PROFIBUS or
Modbus Communication for LF62*.

11.1 Connections with HHT Terminal

Connect the input cable of HHT terminal across the load resistance connected from the current output
terminals (+ and −). Since the cable end is a pair of clips, use a junction terminal or terminal block to
connect with the load resistance. To connect the HHT directly to the flowmeter, use the terminals + and
−. The HHT input cable has no polarity.
See Figures 11.2 and 11.2 for connection examples.
Example of a flowmeter
Converter is built in the housing
Figure 11.1 Connections to the Current Output Line
− 134 −
6 F 8 A 0 9 2 7
4−20mA DC (communication line)
Load resistance
Terminal block or
junction terminal
HHT