Panametrics Sentinel LCT, Руководство пользователя

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Chapter 2. Installation
24 Sentinel LNG User’s Manual
2.4.4 Wiring the Serial Port
The flow transmitter is equipped with a built-in serial communications port. The port is user-selectable to be either
an RS232 or RS485 port. For more information on serial communications refer to the EIA-RS Serial Communications
Manual (916-054). It is recommended to use 12-24 AWG (3.3 - 0.2 mm
2
) twisted pair wiring for single conductors, and
a minimum 18 AWG (1.5 mm
2
) for two conductors per terminal.
2.4.4.1 Wiring the Serial Interface
To wire the serial port, refer to Figure 27 on page 34 and Figure 28 on page 35 and complete the following steps:
1. Disconnect the main power to the meter and remove the wiring access cover.
2. Install the required cable gland in the chosen conduit hole of the electronics enclosure.
3. Feed one end of the cable through the cable gland, wire it to terminal block TB2, and secure.
Figure 15: Serial Connections
WARNING!
To meet CE Mark requirements, all cables must be installed as described in Appendix B,
CE Mark Compliance .
4. If the wiring of the unit has been completed, reinstall the side cover and tighten the set screw.
2.4.5 Wiring the Modbus Communications Line (Optional)
The
Sentinel LNG
uses the RS485 interface with Modbus communications protocol for a maximum line distance up to
4,000 ft (1,200 m). The factory recommends using shielded 18-24 AWG (0.82 - 0.2 mm
2
) cable having a characteristic
impedance of 120 ohms, with 120-ohm termination at each end of the communications line. This interface is also
user-configurable as an RS232 interface.
Connect the two leads and the shield of the
Modbus line to the NET section of terminal block TB2 in the flowmeter . See
Figure 10 on page 20 or Figure 28 on page 35.
SGND (COM)
TD (–)
RD (+)
COM
R (RS485+)
T (RS485–)
TB2 Network Interface