BERTHOLD TECHNOLOGIES Uni-Probe LB 490 - Page 478

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4 Menu Overview Volume 5
 Click OK to confirm the hardware reset.
4.2.30 HART INTERFACE
Input of the polling address.
Parameters Description
Polling address The host terminal uses the "Multidrop Mode" to identify the field device, if
more than one HART
®
device is connected to the same HART
®
loop. This
mode is called multi-detector mode (see page 2-5). Up to 16 HART
®
devices can be installed on one HART
®
loop. Each device must have a dif-
ferent polling number between 1 and 15. If a number higher than 0 is
chosen, the multi-detector mode is selected and the current output is
switched to a fixed current value of 4 mA. Then only one digital HART
®
communication will be available.
IMPORTANT
The current output has a maximum impedance of 500 Ohm.
HART
®
communication is working on a connected impedance of
120 to 500 Ohm. HART
®
communication does not work at a resis-
tance of less than 80 Ohm.
Num Request Preambles Indicates the number of synchronization attempts.