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Overview
The SLN700 SmartLine NCR Level Transmitter is available for operation with HART
communication. This manual addresses the processes to configure a transmitter for HART
communication.
HART
Mode Communication
As indicated in
Figure
1, the output of a transmitter configured for HART
primary modes:
•
Point-to-Point Mode: where one transmitter is connected via a two-conductor,
4-20 mA current loop to one receiver.
•
Multi-Drop Mode: where multiple transmitters are connected through a two-conductor
network to a multiplexed receiver device.
Operating
Range of
Transmitter
(in "implied" EU;
Example:
0-400 in cm
Figure 1: HART
In point-to-point mode, the value of the Primary Variable (PV) is represented by a 4-20 mA current
loop, almost identical to that of a transmitter operating in analog mode. In this case, however, the
analog signal is modulated by Frequency Shift Keying (FSK), using frequencies and current
amplitude that do not affect analog sensing at the receiver. FSK modulation is for sending digital
messages in addition to the analog value. The accuracy of the analog level must be precisely
controlled for accurate sensing. HART
In multi-drop mode, theoretically up to 16 devices in HART
devices in HART
6/7 (addresses 0-63) can exist on the two-conductor network. Practically, the
number of devices in a multi-drop installation is limited due to design constraints.
Revision 1
1 Introduction
Point-to-Point and Multi-drop Value Scaling
communication will not bump process variables.
SLN700 Series HART Option User's Manual
protocol includes two
5 (addresses 0-15) or up to 64
version 7
Page 1
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