Varec 4000 - Manual (Page 12)

Introduction Tank Gauge Transmitter
2 Installation and Operations Manual
1.3 Operation
The ATT uses an incremental counting technique for determining liquid level. An initial level is identified as part of the
calibration procedure. Changes to that level are determined through incremental increases or decreases detected by
the ATT.
The host computer collects measurement information by polling the Advanced Technology Transmitter over a variety
of communication interfaces such as EIA485 and Mark/Space. Several communication protocols are supported. Among
them are Modbus and Mark/Space.
1.4 Configuration
The Varec Model 1200 Handheld Terminal is used to configure the ATT. It connects to the same ATTI bus used to
interconnect other input/output devices to the ATT. There is a special connection located inside the junction box for
the Handheld Terminal.
1.5 Construction
The Advanced Technology Transmitter is housed within an aluminum enclosure. The enclosure and assembly meet
explosion proof requirements and are environmentally sealed to prevent internal exposure to contamination.
Figure 1-2: Model 4000 Advanced Technology Transmitter Assembly
7.5 "
(190 mm)
12 "
(308 mm)
8 "
(203 mm)
6.8 "
(172 mm)
4 "
(101 mm)
3.4 "
(86 mm)
3.7 "
(94 mm)