Failure Mode And Security Jumpers; Failure Mode - Omega PX2088 User Manual

FAILURE MODE AND SECURITY JUMPERS

(Security Jumpers are Available with Smart Transmitters Only)

Failure Mode

As part of normal operation, the Model PX2088 Smart continuously monitors its
own operation. This automatic diagnostic routine is a timed series of checks repeated
continuously. If the diagnostic routine detects a failure in the transmitter, the
transmitter drives its output either below or above specific values depending on the
position of the failure mode jumper or switch.
Smart Transmitters
Whether the output is driven high or low when in failure mode is user-selectable by a
jumper on the transmitter. The values to which 4–20 mA transmitters drive their
output in failure mode depend on whether they are factory-configured to standard or
NAMUR-compliant operation. The values for each are as follows:
Standard Operation
linear output: 3.9 ≤ I ≤ 20.8 mA
fail low:
fail high
NAMUR-Compliant Operation (Option Code C4)
linear output: 3.8 ≤ I ≤ 20.8 mA
fail low:
fail high:
To determine the failure mode configuration of your transmitter, review the failure
mode options using a Model HC275 HART Communicator.
NOTE
The failure mode configuration, whether standard or NAMUR-compliant, is
configured at the factory and can not be changed in the field.
Failure Mode Jumper Locations
Without a meter installed
The failure mode alarm jumper is located on the front side of the electronics
module just inside the electronics housing cover and is labeled ALARM (See
Figure 4-10). Do not remove the instrument cover in explosive atmospheres when
the circuit is alive. Both transmitter covers must be fully engaged to meet
explosion proof requirements.
With a meter installed
The failure mode alarm jumper is located on the LCD faceplate in the electronics
module side of the transmitter housing and is labeled ALARM (See Figure 4-10).
Do not remove the instrument cover in explosive atmospheres when the circuit is
alive. Both transmitter covers must be fully engaged to meet explosion proof
requirements.
Analog Transmitters
If self diagnostics detect a sensor or microprocessor failure, the analog signal is
driven low to alert the user (I ≤ 3.6 mA or V≤ 1V for output Code M).
3.75 mA
21.75 mA
3.6 mA
22.5
4-11