Hart Variable Assignment; Communication / Hart Tag / Device Address - ABB TTF350 Operating Instructions Manual

2-sensor input functionality / Dual sensor mode
The disadvantage of D/A analog output compensation is that the HART signal prior to the D/A
conversion without correction differs from the analog output signal after D/A conversion due to
the incoming error correction of the superordinate system. As a result, the HART value
displayed is slightly different from the output signal current.
8.6

HART variable assignment

Because every HART devices can basically transmit four variables, the measurement value to
be transmitted via HART signal can be specified in the menu Device / Configuration when using
the TTF350 DTM or EDD for device setup.
The primary variable is mapped to the 4 ... 20 mA output as well as the secondary, tertiary and
quaternary variables.
The following values can be assigned to variables:
-
-
-
-
-
-
-
-
-
8.7

Communication / HART tag / Device address

For ease of identification, each HART device features a configurable 8-digit HART tag.
Standard devices are come with the HART tag "TI XXX".
(When storing HART tags with more than 8 digits in the device, use the "Report" parameter,
which supports up to 30 characters.)
In addition to the HART tag, each device has a HART address.
This address is set by default to zero, in which state the device operates in HART standard
communication mode (point-to-point operation). When an address in the range 1 to 15 is used,
the device switches to HART multidrop mode. This operating mode enables users to connect up
to 15 devices in parallel to a power supply.
In multidrop mode, an analog output signal that matches the process temperature is not
available. The output signal in multidrop mode is, basically, a constant 4 mA and is used
exclusively for the power supply.
In multidrop mode, sensor or process data information is available only as a HART signal.
In addition to point-to-point and multidrop modes, the third type of HART communication is burst
mode. When burst mode is activated, the device continuously transmits a HART telegram
containing reading information approx. every 500 ms without prompting by HART command.
In burst mode as with point-to-point mode, the analog output signal is available and matches the
primary variable defined during setup.
50
Elec. input 1
Elec. input 2
Sensor 1 process data
Sensor 2 process data
Differential sensor 1 – sensor 2
Differential sensor 2 – sensor 1
Average of sensor 1 + sensor 2
Redundancy
Electronic unit temperature
TTF350 OI/TTF350-EN