wtw DIQ/S 182-PR, System Operating Manual

Page: 101 / 146

System 182 Relay outputs
6 - 17 ba75503e07 04/2012
6.4.4 Limit indicator
Function The characteristic of the limit indicator is laid down in the Limit value
UL , Limit value LL , Hysteresis UL and Hysteresis LL settings. The
fundamentals of the function are described in the introductory chapter
(see section 6.3.2).
In order to set up the Limit indicator function for a relay output, the relay
output must be linked with a sensor (see section 6.2.1).
Settings
Setting Selection/Values Explanation
Limit values UL main variable
LL main variable
UL adjoining var.
LL adjoining var.
Main variable
designates the actual
measured parameter
of the sensor (e.g.
pH, oxygen, etc.).
Adjoining variable
designates an
additional measured
parameter (e.g.
temperature).
Limit value UL within the measuring
range (sensor-
dependent) Any upper or lower
limiting value
Limit value LL
Hysteresis UL 0 - 10 % of the
measuring range Hysteresis for upper
or lower limiting value
Hysteresis LL
Behavior at error Open
Close
Unchanged The relay opens,
closes, or remains
unchanged in case of
system errors or
sensor errors (see
page 6-25).
Action Open
Close Relay action
Switching delay 0 ... 3600 s The time period for
which a limiting value
must be exceeded
before the relay
operates.
Prevents frequent
switching for
measured values that
are close to the
limiting value.