Emerson 8700 Series, Reference Manual

Page: 14 / 136

Reference Manual
00809-0100-4793, Rev CA
August 2004
Rosemount 8742C
2-2
TRANSMITTER
SYMBOLS
Caution Symbol — Check product documentation for details.
Protective conductor (grounding) terminal.
PRE-INSTALLATION
Before installing the Rosemount 8742C Magnetic Flowmeter Transmitter,
there are several pre-installation steps that should be completed to make the
installation process easier. They include identifying the options and
configurations that apply to your application, setting the hardware switches if
necessary, and consideration of physical requirements.
The mounting site for the 8742C should provide enough room for secure
mounting, easy access to the conduit ports, and full opening of the transmitter
covers.
To ensure maximum transmitter life, avoid excessive heat and vibration.
Typical problem areas include high-vibration lines with integrally mounted
transmitters, warm-climate installations in direct sunlight, and outdoor
installations in cold climates. To avoid potential problems, remotely mounted
transmitters may be installed in the control room. This protects the electronics
from the harsh environment and provides easy access for configuration or
service.
The Rosemount 8742C transmitter requires external power regardless of
whether it is mounted remotely or integrally to the flowtube. Access to a
suitable power source must be ensured.
Identify Options and
Configurations
The standard application of the Rosemount 8742C includes a F
OUNDATION
fieldbus output. Be sure to identify options and configurations that apply to
your situation, and keep a list of them nearby for consideration during the
installation and configuration procedures.
Hardware Switches
The Rosemount 8742C electronics board is equipped with two
user-selectable hardware switches. These switches set Simulate Enable and
Transmitter Security. The standard configurations for these switches when
shipped from the factory are as follows:
Simulate Enable:
Off
Transmitter Security:
Off
Definitions of these switches and their functions are provided below. The
switches are located on the outerboard of the electronics transmitter stack.
See Figure 2-1 on page 2-3.
Simulate Enable
The simulate enable switch is used in conjunction with the Analog Input (AI)
function block. The switch is used to enable flow measurement simulation.
The switch is also used as a lock-out feature for the AI function block. To
enable the simulate enable feature, the switch must transition form OFF to
ON
after
power is applied to the transmitter, preventing the transmitter from
being accidentally left in simulate mode.
Transmitter Security
After you configure the transmitter, you may want to protect the configuration
data from unwarranted changes. Each transmitter is equipped with a security
switch that can be positioned ON to prevent the accidental or deliberate
change of configuration data.