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Connecting
5.2 Connecting the transmitter
SITRANS P300 with HART communication
5-2
Operating Instructions, 06/2005, A5E00359579-02
Note
To improve the reliability:
•
Install the signal cable separately from cables with voltages > 60 V.
•
Use cable with twisted strands.
•
Stay away from large electrical systems.
•
Use shielded cable to guarantee the full specification according to HART.
•
Connect a load of at least 230 ohms into the signal circuit in sequence in order to guarantee fault-
free HART communication. When using supply isolation for SMART transmitters, for example:
Siemens 7NG4021 a load is already installed in the device.
5.2
Connecting the transmitter
Requirement
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Figure 5-1
Connecting
(1)
Supply terminals
(3)
Auxiliary power U
H
(2A) Shield support with plastic cable gland
(4)
Load
(2B) Shield on cable gland
Note
The following values can be set for the load:
•
230 to 1100 Ω for the HART communicator
•
230 to 500 Ω for the HART modem