Yokogawa Data Acquisition with PID Control CX2000 User Manual

Page 77

1-65

IM 04L31A01-01E

Explanation of Functions

Alarm Hysteresis

You can set a width (hysteresis) to the values used to activate and release alarms.
Alarm hysteresis prevents frequent activation and release of alarms when the measured
value is unstable around the alarm value. The hysteresis is fixed to 0.5% of the
measurement span (display scale width if the range is set to scale).
It is applied only on alarms set to upper/lower limit alarm on measurement channels, and
the function can be turned ON/OFF.
Factory default setting: Hysteresis ON

Alarm
setting

Alarm release

Measured value

Alarm occurrence

Upper limit alarm

Lower limit alarm

Measured value

Alarm release

Hysteresis
(Approx. 0.5%)

Alarm occurrence

Alarm
setting

Alarm Relay Output

Relay Output ON/OFF
When an alarm occurs, you can output relay signals from the alarm output terminal
(ALARM) on the measurement alarm option terminal block, the control output terminal
block, the relay contact output on the control DIO expansion terminal block, or the
transistor output terminal (DIGITAL OUT). You can also turn the internal switches ON
(style number S3 or later).

Reflash Alarm
This function is used to notify alarms occurring after the relay is activated on the first
alarm when multiple alarms are assigned to a single alarm output relay. When this
function is turned ON, the output relay is temporarily (approx. 500 ms) released when
alarms after the first alarm occur. The initial setting is [Off] (not use reflash alarm).
The reflash alarm function is set only on output relays I01, I02, and I03.

Alarm

1 channel

3 channels

2 channels

Alarm output relay
(Reflash alarm ON)

Alarm output relay
(Reflash alarm OFF)

Approx.

500 ms

Approx.

500 ms

Note

If the reflash alarm is set, I01 to I03 become dedicated reflash alarms regardless of the

number of alarm output relays. Therefore, relays I01 to I03 operate as OR logic (see “AND/

OR of Alarm Output Relays”) and non-hold (see

“Hold/Non-hold Operation of Alarm Output

Relays”

) regardless of the settings made in “AND/OR of alarm output relays” and “Hold/Non-

hold operation of the alarm output relay.”

1.15 Measurement Function > Measurement Alarm Related Settings