ABB LevelMaster 7100, Руководство пользователя, Страница: 15 / 100

LevelMaster 7100 User manual 2105835 Rev AA | 5
Level sensor
Level sensing involves the coil assembly and the float(s). The coil assembly senses the movement and position of the floats as
they slide up or down the casing when the fluid level increases or decreases. The signal generated from this interaction is read
by the electronics board and processed to determine the actual fluid level in units of length.
Temperature sensor
Temperature is provided along with fluid level readings. A standard configuration includes one temperature sensor located 12
inches (304.8 mm) from the bottom of the sensor tube which reads accurately to within 1
°
F (0.6
°
C).
Floats
Level(s) are sensed by the movement of one or two floats which slide up and down the sensor casing as the fluid level changes.
Two floats are used when the vessel contains fluids with two different densities such as oil and water. Each float will accurately
measure the level of its respective fluid over the full vertical range of the sensor tube with a relative accuracy to the nearest
±
0.1 inch (2.5 mm), optional
±
0.05 inch (1.27mm).
Floats have an outer material that can withstand most solvents and chemicals.
Electronics board
The electronics board is installed inside of the enclosure or junction box assembled at the top end of the unit. The board stores
the configuration of the unit, calibration data and measurement data. The board is connected to the sensor assembly.
The board is the termination point for power and communications through its onboard ports. The onboard port(s) provide the
power and communication connection points to operate the LevelMaster. Depending on the board type, there may be a single
connector handling both power and communications or two separate connectors for each. The ports have terminal connectors
that are removable for convenient field wiring.
IMPORTANT NOTE: Access to the onboard ports for wiring or local connection requires removal of the enclosure
cover.
Sensor port
An onboard 16-pin port provides the connection point for the sensor assembly ribbon cable and connector. The cable is run
through the neck of the enclosure from the sensor to the board. The onboard connector is keyed for correct one-way insertion of
the sensor cable connector. The cable can be unplugged as needed for sensor testing or board replacement or reconfiguration
during troubleshooting or maintenance procedures.
Power port
The onboard power port provides the connector to supply power to the LevelMaster. The power port supports connections to:
An external power supply or
ABB Totalflow control or measurement equipment such as remote controllers and flow computers.
Serial communications (RS-485) port
The onboard serial port is used for communication with other devices. The LevelMaster uses RS-485 hardware protocol and
standard ASCII softfware protocol to communicate at speeds of 1200, 9600, and 19200 bps.
The RS-485 port supports connections to:
A laptop or PC: for direct communication for local operator setup or monitoring or measurement data
Additional LevelMasters when daisy-chained as part of an RS-485 bus
ABB Totalflow remote controllers and flow computers supporting the ASCII communication protocol
IMPORTANT NOTE: Wiring distance from the LevelMaster to a host controller is limited by RS-485 specifications and
by the use of safety barriers required in hazardous locations. For details see Table 5, Wiring limits on the RS-485 bus ,
and Table 6, Wiring limitations when using barrier boards .