ABB REM 54 Series, Technical Reference Manual

Page: 51 / 110

1MRS750915-MUM
REM 54_
51
Machine Terminal
Technical Reference Manual, General
5.1.7.4. Oscillation suppression
Oscillation suppression is used to reduce the load from the system when, for some
unrecognized reason, a digital input starts oscillating. A digital input is regarded as
oscillating if the number of valid status changes (= number of events after filtering)
during 1 second is greater than the set value
Input osc. level
(Oscillation
level). During oscillation, the digital input is blocked (status is invalid) and an event
is generated. The state of the input will not change when it is blocked, i.e. its state
depends on the condition before blocking.
The digital input is regarded as non-oscillating if the number of valid status changes
during 1 second is less than the set value of
Input osc. level
minus the set
value of
Input osc. hyst.
(Oscillation hysteresis). Note that the oscillation
hysteresis must be set lower than the oscillation level to enable the input to be
restored from oscillation. When the input returns to a non-oscillating state, the
digital input is deblocked (status is valid) and an event is generated.
5.1.7.5. Attributes of a digital input for machine terminal configuration
The validity of the digital input (invalidity), the status of the input (value), the time
tag for the status change (time) and the counter value of the input can be issued for
each digital input by the attributes BI#IV, BI#, BI#Time and BI#Count, where #
denotes the number of the input. These attributes are available in the machine
terminal configuration and can be used for different purposes.
The example below shows how the attributes of the digital input 1 (PS1_4_BI1 on
PS1 module) of the machine terminal are named for the configuration:
PS1_4_BI1IV; digital input invalidity
PS1_4_BI1; digital input value
PS1_4_BI1Time; time tag
PS1_4_BT1Count; counter value
Invalidity (BI#IV)
When a digital input oscillates, the invalidity attribute IV changes to TRUE (1) and
the input is blocked. The digital input is regarded as being blocked and oscillating if
the number of status changes per second exceeds the set
Input osc. level
value (events/s).
When a digital input does not oscillate, the invalidity attribute IV changes to FALSE
(0) and the input becomes operative. The digital input is regarded as being operative
and non-oscillating if the number of status changes per second is less than the set
Input osc. level
value minus the set
Input osc. hyst.
value (events/s).
Parameter Values Default
Input osc. level 2...50 events/s 50 events/s
Input osc. hyst. 2...50 events/s 10 events/s
Unlike most parameters for digital I/O cards, the parameters
Input osc. level
and
Input osc. hyst.
can be found in
the menu
Configuration/General.