
4
Reference Manual
00809-0100-4808, Rev DA
Transmitter Functions
October 2016
Transmitter Functions
2.3
Failure mode alarm
Rosemount 3051N Transmitters automatically and continuously perform self-diagnostic routines. If the
self-diagnostic routines detect a failure, the transmitter drives its output outside of the normal
saturation values. The transmitter will drive its output low or high based on the position of the failure
mode alarm jumper. See
Table 2-1
for failure mode and saturation output levels. To select alarm
position, see
“Configuring transmitter alarm and security jumper” on page 5
.
Table 2-1. Standard Alarm and Saturation Values
Note
The actual transmitter mA output values can be altered by performing an analog output trim.
Note
When a transmitter is in an alarm condition, the hand-held HART Communicator indicates the analog
output the transmitter would drive if the alarm condition did not exist. The transmitter will alarm high in
the event of failure if the alarm jumper is removed.
2.3.1
Alarm level verification
Transmitters allow verification testing of alarm current levels. If you replace the LCD display meter,
reconfigure or make any changes to the transmitter, verify the transmitter alarm level before you return
the transmitter to service. This feature is also useful in testing the reaction of your control system to a
transmitter in an alarm state. To verify the transmitter alarm values, perform a loop test and set the
transmitter output to the alarm value (see
Table 2-1
and
“Loop test” on page 14
).
2.4
Transmitter security
There are three security methods with the Rosemount 3051N Transmitter.
1. Security Jumper: prevents all writes to transmitter configuration.
2. Local Keys (Local Zero and Span) Software Lock Out: prevents changes to transmitter range points via
local zero and span adjustment keys. With local keys security enabled, changes to configuration are
possible via HART.
3. Physical Removal of Local Keys (Local Zero and Span) Magnetic Buttons: removes ability to use local
keys to make transmitter range point adjustments. With local keys security enabled, changes to
configuration are possible via HART.
Note
If the security jumper is not installed, the transmitter will continue to operate in the security OFF
configuration.
Level
4–20 mA Saturation
4–20 mA Alarm
Low
3.9 mA
3.75 mA
High
20.8 mA
21.75 mA
Содержание Rosemount 3051N
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