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OPERATING MANUAL TMU / UMC3
4.8.2.3
HART®
A number of connection possibilities are available for HART
®
communication, with the condition that the
loop resistance is less than the maximum load specified in Section 4.8.2, “Current outputs” on page 39. The
HART
®
interface is connected via terminal 11 and 12 or 41 and 42 respectively. The minimum load
impedance of 250 Ω must be adhered to.
For information regarding operation of the transmitter using the HART
hand-held terminal, see refer to the
supplementary manual; ”UMC-HART_BA_20.01_en“.
Communication via Siemens PDM
®
PDM
®
is the configuration software of Siemens that is used to operate HART
®
or Profibus PA compatible
devices.
To connect a desktop or laptop computer to the UMC3, a HART
®
interface is required in addition to
communication software such as PDM. The HART
®
interface, which has two connections, converts the levels
of the RS 232 interface or USB interface into an FSK signal (frequency-shift keying).
For further details see section 3.4.10, “Connection to the transmitter” on page 23
4.8.2.4
Damping
The damping of the output signals is programmable from 1 to 60 seconds.
The standard factory setting is 3 seconds.
4.8.2.5
Error indication
An error in, or failure of the meter can be indicated via the current outputs or the status output. The current
outputs can be set to a failure signal (alarm) of I < 3.8 mA or I > 22 mA.
The status output can be configured as a make or break contact.
4.8.2.6
Low flow cut-off
The low flow cut-off can be set to values between 0 and 20% via the menu. The set value is a percentual
value of the upper-range setting. If the measured value is lower than the set cut-off, the flow rate will be
set to 0.0 (kg/h). This results in the analogue output being set to 0/4 mA, and the pulse output will cease
generating pulses.