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502 010 05
5.4
Input signal
The input signal is galvanically iso-
lated. To activate the input, a voltage
of minimum 18 V must be connected
to the terminals with the right polariza-
tion. This voltage may be supplied
from either the internal voltage supply
or an external power supply.
5.5
Temperature signal, Pt100
A standard Pt100 temperature sensor may be connected to the Flow Transmitter. The tem-
perature sensor must be connected with a 4-wire cable all the way from the sensor to the
terminal box. This must be done to avoid errors introduced by the cable length, junctions and
connections. The cable that connects the Pt100 temperature sensor to the Flow Transmitter
must not exceed 25 m.
Note 1: The sensor wires must not be connected to the sensor housing (grounded).
Note 2: If a temperature sensor is not used, the terminals 9-10-11-12 must either be con-
nected together or left unused in order to avoid errors in the flow measurement.
Do not connect any other kind of resistors except Pt100 sensors, as a resistance
out of range could influence the results of the measurements without your knowl-
edge. Due to this fact, it must also be ensured that the 4-wire cable connections
between the sensor and the terminals are steady and reliable.
5.6
Connecting the display unit, PD 210
The display unit is connected to the Flow Transmitter with a two wire twisted cable, up to a
length of 100 m. The display unit is supplied with power via this cable. It also carries the ex-
change of data between the Flow Transmitter and the display unit.
The communication speed between the Flow Transmitter and the PD 210 display unit is 300
bit/sec, resulting in a updated data readout of approx. every second.
To improve the electrical noise immunity with long length cables, a shielded cable is recom-
mended. In this case the shield should be connected to terminal 8 at the terminal box and not
connected at the display unit.
5.7
P-NET fieldbus connections
P-NET is standardised internationally (IEC 61158 Type 4). Up to 125 units can be connected
to the fieldbus, where a device may be a PD 340 Flow Transmitter, a Flowmeter Display or
another P-NET interface module. The P-NET interface is galvanically isolated. The fieldbus
cable is a twisted pair cable with shield, and the shield is used as a potential equalizer be-
tween the driver/receiver circuits in the nodes connected to the fieldbus.
24/55
Approx.
5 kOhm
Flow Transmitter, PD 340
19+
Input voltage < 6 V: OFF
Input voltage > 18 V: ON
20-
551 112 02
Manual
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