D/A Analog Output Adjustment (4 And 20 Ma Trim)17; Hart Variables; Communication / Hart Tag / Device Addressing17 - ABB ttr200 Operating Instruction

9.3.2 D/A analog output adjustment (4 and 20 mA trim)
D/A analog output adjustment is used to compensate for
errors in the current input of the higher-level system. D/A
analog output adjustment for the transmitter can be used to
modify the loop current so that the desired value is displayed
in the higher-level system.
Error compensation for the higher-level system is possible at
the lower range value with 4 mA and / or 20 mA (single-point
error correction: offset or two-point error correction: offset +
linear gradient).
The D/A analog output adjustment can be accessed in the
DTM via the menu path "Device / Maintenance / Adjustment".
Prior to analog adjustment, it is necessary to determine the
loop current values based on iterative entry of current values in
simulation mode; the higher-level I/O system displays exactly
4.000 mA or the lower range limit temperature, and
20.000 mA or the upper range limit temperature. The current
loop values must be measured using an ammeter and
recorded.
The lower range limit value or 4.000 mA +/- 16 μA must then
be simulated in D/A analog output adjustment mode using
sensor simulation. Following this, the iteratively calculated
current value at which the higher-level system displays exactly
4.000 mA or the lower range limit value must be entered as an
adjustment value. Proceed in a similar manner for the upper
range value or 20.000 mA.
After this correction, the AD converter error of the higher-level
system is corrected by the DA converter of the transmitter. For
the higher-level system, the value of the analog 4 ... 20 mA
output signal and the digital HART signal now match.
The adjustment should be repeated when connecting the
transmitter to another input of a higher-level system.
Change from two to one column
9.3.3

HART variables

The transmitter provides three HART variables. The HART
variables are assigned the following values:
— Primary HART variable: process value
(The primary HART variable is assigned permanently to the
analog output and, accordingly, to the 4 ... 20 mA signal.)
— Secondary HART variable: electronic unit temperature
— Tertiary HART variable: electrical input
9.3.4 Communication / HART TAG / device addressing
For ease of identification, each HART device features a
configurable 8-digit HART TAG. All devices are supplied with
the HART TAG "TI XXX" as standard. (When storing HART tags
with more than 8 digits in the device, use the "Report"
parameter, which supports up to 32 characters.)
In addition to the HART TAG, each device has a HART
address. This address is set to 0 by default, which means that
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 the "HART Multidrop mode".
This operating mode enables users to connect up to
15 devices to a power supply unit in parallel.
In multidrop mode, an analog output signal that matches the
process temperature is not available.
The output signal in multidrop mode is a constant 3.6 mA and
is used exclusively for the power supply. In multidrop mode,
sensor or process data information is available only as a HART
signal.
TTR200 | OI/TTR200-EN Rev. B 17