Rosemount 8712, Справочное руководство

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Reference Manual
00809-0100-4664, Rev BA
January 2010
2-5
Rosemount 8712
Changing Hardware Switch Settings
In most cases, it is not necessary to change the setting of the hardware
switches. If you need to change the switch settings, complete the steps
outlined in the manual.
Definitions of these switches and their functions are provided below. If you
determine that the settings must be changed, see below.
Failure Alarm Mode
If the 8712 experiences a catastrophic failure in the electronics, the current
output can be driven high (23.25 mA) or low (3.75 mA). The switch is set in
the
HIGH (23.25 mA) position when it is shipped from the factory.
Internal/External Analog Power
The Rosemount 8712 4–20 mA loop may be powered internally
or by an external power supply. The internal/external power supply switch
determines the source of the 4–20 mA loop power.
Transmitters are shipped from the factory with the switch set
in the
INTERNAL position.
The external power option is required for multidrop configurations. A 10–30 V
DC external supply is required and the 4-20mA power switch must be set to
“EXT” position. For further information on 4–20 mA external power, see
Connect 4–20 mA Loop External Power Source on page 2-9.
Transmitter Security
The security switch on the 8712 allows the user to lock out any configuration
changes attempted on the transmitter. No changes to the configuration are
allowed when the switch is in the
ON position. The flow rate indication and
totalizer functions remain active at all times.
With the switch in the ON position, you may still access and review any of the
operating parameters and scroll through the available choices, but no actual
data changes are allowed. Transmitter security is set in the
OFF position
when shipped from factory.
Changing Hardware Switch Settings
In most cases, it is not necessary to change the setting of the hardware
switches. If you need to change the switch settings, complete the steps
below:
NOTE
The hardware switches are located on the non-component side of the
electronics board and changing their settings requires opening the electronics
housing. If possible, carry out these procedures away from the plant
environment in order to protect the electronics.
1. Disconnect power to the transmitter.
2. Loosen the housing door screw and open the housing door.
3. Identify the location of each switch (see Figure 2-2).
4. Change the setting of the desired switches with a small screwdriver.
5. Close the housing door and tighten the housing door screw.