SMAR LD291, Инструкция по эксплуатации и техническому обслуживанию

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Section 3
3.1
CONFIGURATION
The
LD291 Intelligent Pressure Transmitter is a digital instrument with the most up-to-date features a
measurement device can possibly have. Its digital communication protocol (HART

) enables the
instrument to be connected to a computer in order to be configured in a very simple and complete way.
Such computers connected to the transmitters are called HOST computers. They can either be Primary
or Secondary Masters. Therefore, even the HART

being a master-slave type of protocol, it is possible
to work with up to two masters in a bus. The Primary HOST plays the supervisory role and the
Secondary HOST plays the Configurator role.
The transmitters may be connected in a point-to-point or multidrop type network. In a point-to-point
connection, the equipment must be in its "0" address so that the output current may be modulated in 4
to 20 mA, as per the measurement. In a multidrop network, if the devices are recognized by their
addresses, the transmitters shall be configured with a network address between "1" and "15. In this
case, the transmitter’s output current is kept constant, with a consumption of 4 mA each. If the
acknowledgement mechanism is via Tag, the transmitter’s addresses may be "0" while their output
current is still being controlled, even in a multidrop configuration.
In the case of the LD291 the "0" address causes the LD291 to control its output current and addresses
"1" through "15" place the LD291 in the multidrop mode with current control.
NOTE
In the case of multidrop network configuration for classified areas, the entity parameters allowed for
the area shall be strictly observed. Therefore, the following shall be checked:
Ca
≥ Σ
Ci
j
+ Cc La
≥ Σ
Li
j
+ Lc
Voc
≤
min [Vmax
j
] Isc
≤
min [Imax
j
]
Where:
Ca, La - Barrier Allowable Capacitance and Inductance
Ci
j
, Li
j
- Non protected internal Capacitance/Inductance of transmitter j (j = 1 up to 15)
Cc, Lc - Cable capacitance and Inductance
V
oc
- Barrier open circuit voltage
I
sc
- Barrier short circuit current
Vmax
j
- Maximum allowable voltage to be applied to the instrument j
Imax
j
- Maximum allowable current to be applied to the instrument j
The LD291 Intelligent Pressure Transmitter includes a very encompassing set of HART

Command
functions that make it possible to access the functionality of what has been implemented. Such
commands comply with the HART

protocol specifications, and are grouped as Overall Commands,
Common Practice Controls Commands and Specific Commands. A detailed description of such
commands may be found in the manual entitled HART

Command Specification - LD291 Intelligent
Pressure Transmitter.
Smar developed the CONF401 and HPC301 software, the first one works in Windows platform ( 95, 98,
2000, XP and NT ) and UNIX . The second one, HPC301 , works in the most recent technology in PDA´s.
They bring easy configuration and monitoring of field devices, capacity to analyze data and to modify
the action of these devices.
The operation characteristics and use of each one of the
configurators are stated on their respective manuals.
Figures 3.1 and 3.2 show the front of the Palm and the CONF401 screen, with the active configuration.