Emerson Process Management Series 9110, CI-9110 Analog Failure Modes Fail Hold & Fail Zero

Table 3-3 - Switch SW2 (2-5), Output Rate Of Change

SW2-5		SW2-4		SW2-3		SW2-2		Nominal
								Rate Of Change, ±15%
Close	Close		Close		Close		1.8 Min. Full Scale Travel
Close	Close		Close		Open			5.5 Min. Full Scale Travel
Close	Close		Open			Close		11.0 Min. Full Scale Travel
Close	Close		Open		Open			16.5 Min. Full Scale Travel
Close	Open			Close		Close	21.9 Min. Full Scale Travel
Close	Open			Open		Close		32.9 Min. Full Scale Travel
Close	Open			Open		Open		38.3 Min. Full Scale Travel
Open		Close		Close	Open			43.8 Min. Full Scale Travel
Open		Close		Open		Open		60.3 Min. Full Scale Travel
Open		Open		Close		Close		65.85 Min. Full Scale Travel
Open		Open		Close		Open		69.4 Min. Full Scale Travel

3.7 ANALOG FAILURE MODES (Fail Hold & Fail Zero)

Analog models have an "Analog Fault Detector" feature which, when selected by jumpers on the Termination Board, provides a selection of two failure modes, Fail Hold and fail Zero. In the "Fail Hold" mode, the Analog Fault will stop the stepper motor at the last pressure output value prior to the loss of the analog input signal. Note that the Guard terminals are not available for external usage in this mode. The Fault Detector trip point for this mode is factory set at 0.8 volts which corresponds to -5% of fullscale.

In the alternate "Fail Zero" mode, the Guard terminals are available for use with an external signal. In this mode, the analog input signal is “enabled” by a signal at the Guard terminal. If the input drops to zero while the Guard signal remains TRUE, the output will also go to zero.

The selection of either failure mode is accomplished via two jumpers, W1 and W2. These jumpers are located on the Termination Board as shown in Figure 3-2. These jumpers may be plugged in position A or B; however, both jumpers must always be in the same position.

The configurations are selected as follows:

FAIL-HOLD MODE

(Both Jumpers in A position)

In the "A" position, a failure of the AI Command Input (value fails below 0%) causes the pressure output to remain at the value of the last valid sampling period. This condition is maintained until a normal AI is received.

Board Setup 3-6 CI-9110