Section 3
3.1
CONFIGURATION
The Temperature Intelligent Transmitter TT301 is a digital device bearing the most advanced features a
measurement apparatus can offer. A HART
digital communication protocol permits the device to be
connected to an external computer for a simple and complete configuration. These computers,
connected to the transmitters, are called HOST computers and may be a Primary or Secondary Master
type. Although HART may be a master/slave protocol, it may coexist with up to two masters in a field
bus. Generally, the Primary HOST stands for a Supervisory and the Secondary HOST is used as a
Configurator.
Transmitters, on the other hand, may be connected to a point-to-point or a multi-drop network. In a
point-to-point network, the equipment should have its address set at “0”, so that the output current is
modulated from 4 to 20 mA, according to the measurement performed. In a multidrop network, the
transmitters should be configured on a network address between “1” and “15”, if the identification
devices work via address. In this case, the transmitter’s output current must be constant, each
transmitter consuming 4 mA. If the identification mechanism is done via Tag, the transmitters may be
addressed at “0” and control their current output, even on a multidrop configuration.
The TT301 may be configured both for Transmitter and Controller and the HART addressing may be
used as follows:
TRANSMITTER MODE: The TT301 controls the current output, while the “1” to “15” addresses
adjust the TT301 on multidrop mode setting the output current control on 4 mA.
CONTROLLER MODE: The TT301 always controls the output current according to the value
calculated for the Manipulated Variable, regardless of its address value on the net.
When configured in multidrop for the classified areas the entity parameters allowed for the area must be
strictly observed. So, verify that:
Ca Cij + Cc La Lij + Lc
Voc min [Vmaxj] Isc min [Imaxj]
Where:
Ca, La = capacitance and inductance permitted in bus;
Ci
j
, Li
j
= transmitter capacitance and inductance r j (j=1, 155), without internal protection;
Cc, Lc = cable capacitance and inductance;
Voc = open circuit tension of the intrinsic safety barrier;
Isc = short circuit tension of the intrinsic safety barrier;
Vmax = maximum permissible tension to be applied on the r j transmitter;
Imax = maximum permissible tension to be applied on the r j transmitter.
The TT301 Intelligent Temperature Transmitter presents a comprehensive set of HART Commands that
permit accessing any implemented functionality. These commands comply with the HART protocol
specifications and are grouped in Universal Commands, Common Practice Commands and Specific
Commands.
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.
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