Toshiba LF516 - Manual (Page 132)

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11.Communications Function
LF546 Electromagnetic Flowmeter converter 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 LF546 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 communication board to the converter, the converter can be used as
a PROFIBUS-PA slave device to communicate digital data with PROFIBUS master device .
For details of PROFIBUS communication, refer to the instruction manual of PROFIBUS
communication for LF546.
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.
Figure 11.1 Connections to the Current Output Line
4 −20mA DC (communication line)
Load resistance
Terminal block or
junction terminal
HHT
Example of a flowmeter
Converter is built in the housing