Alarm Hysteresis; Standby Sequence - Omron E5 Getting Started Manual

Alarm Hysteresis

Example of a 2-point
Temperature Input
Shift
Lower-limit
C
insl
Temperature
Input Shift
-27.3
Value
Upper-limit
C
insh
Temperature
Input Shift
52.7
Value
4-2

Alarm Hysteresis

4-2-1

Standby Sequence

Restart
68
In this example, we use the ES1B K 0 to 260°C specification. In equations 1
and 2, the set temperature lower limit YL is 0°C and the set temperature upper
limit YH is 260°C. Check the temperature of the control target.
The temperature input offset values can be calculated as shown below when
the Controller readout Y1 is 40°C for a room temperature X1 of 25°C and
when the Controller readout Y2 is 105°C for a set point temperature X2 of
110°C.
Lower-limit Temperature Input Shift Value
0 − 40
× {(110 − 105) − (25 − 40)} + (25 − 40) = −27.3 (°C)
insl =
105 − 40
Upper-limit Temperature Input Shift Value
260 − 40
× {(110 − 105) − (25 − 40)} + (25 − 40) = 52.7 (°C)
insh =
105 − 40
• The hysteresis of alarm outputs when alarms are switched ON/OFF can
be set as follows:
Upper-limit alarm
ON
OFF
Alarm value
• Alarm hysteresis is set independently for each alarm in the Alarm Hyster-
esis 1 to Alarm Hysteresis 3 parameters (initial setting level).
• The default is 0.2 (°C/°F) for Controllers with Thermocouple/Resistance
Thermometer Universal Inputs and 0.02% FS for Controllers with Analog
Inputs.
• The standby sequence can be used so that an alarm will not be output
until the process value leaves the alarm range once and then enters it
again.
• For example, with a lower limit alarm, the process value will normally be
below the set point, i.e., within the alarm range, when the power supply is
turned ON, causing an alarm to be output.
If the lower limit alarm with a standby sequence is selected, an alarm will
not be output until the process value increases above the alarm set value,
i.e., until it leaves the alarm range, and then falls back below the alarm set
value.
• The standby sequence is canceled when an alarm is output. It is, how-
ever, restarted later by the Standby Sequence Reset parameter
(advanced function setting level). For details, refer to the Standby
Sequence Reset parameter in SECTION 5 of H156 Parameters.
Lower-limit alarm
Alarm hysteresis
ON
OFF
Section 4-2
Alarm hysteresis
Alarm value