xLogic has a maximum tolerance of ± 0.02 %. When 0.02 %
of the time T is smaller than 0.02 seconds, the maximum
deviation is 0.02 seconds.
Example: The maximum tolerance per hour (3600
seconds) is ±0.02%, which is proportional to ± 0.72
seconds. The maximum tolerance per minute (60 seconds)
is ± 0.02 seconds.
The accuracy of the timer (weekly/yearly timer)
The maximum timing inaccuracy is ± 5 s/day.
Backup of the Real-time Clock
Because the internal real-time clock of a CPU is backed
up, it continues operation after a power failure. The
ambient temperature influences the backup time. At an
ambient temperature of 25°C, the typical backup time of a
CPU is 100 hours.
Retentivity
The switching states and counter values of SFs can be set to
be retentive. This means that current data is retained after
a power failure and that the block resumes operation at
the point at which power was lost. The timer is not reset
but resumes operation until the time-to-go has expired,
for example, to enable this response, however, the relevant
functions must be set retentive.
SFs hours counter, weekly timer, yearly timer and PI
controller are always retentive.
Parameter Protection
In the parameter protection settings, you can determine
whether or not the parameters can be displayed and
edited in xLogic parameter assignment mode. Two options
are available:
- The parameter attribute permits read/write access in
parameter assignment mode(default).
- The parameter settings are read–/write–protected in
parameter assignment mode and can be edited only via
xLogicsoft.
Calculating the Gain and Offset of Analogue Values
A sensor is connected to the analogue input and converts
a process variable into an electrical signal. This value of
signal lies within the typical range of this sensor. xLogic
always converts the electrical signals at the analogue input
into digital values from 0 to 1000. A voltage of 0 to 10 V
(or current signal 0/4…20mA) at input AI is transformed
internally into a range of values from 0 to 1000. An input
voltage exceeding 10 V is shown as internal value 1000.
Because you cannot always process the range of values
from 0 to 1000 as predetermined by xLogic, you can
multiply the digital values by a gain factor and then shift
the zero of the range of values (offset). This allows you to
output an analogue value to the xLogic display, which is
proportional to the actual process variable.
Table 20 Gain and Offset
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