Beckhoff EP3356-0022, Documentation

Page: 36 / 91

Commissioning/Configuration
EP3356-0022 36 Version: 1.4
Legend
Name Designation CoE Index
U
Diff
Bridge voltage/differential voltage of the sensor element, after averager
and filter
U
ref
Bridge supply voltage/reference signal of the sensor element, after
averager and filter
A
i
Internal gain, not changeable. This factor accounts fort he unit
standardisation from mV to V and the different full-scale deflections of the
input channels
C
n
Nominal characteristic value of the sensor element (unit mV/V, e.g.
nominally 2 mV/V or 2.0234 mV/V according to calibration protocol)
8000:23 [
}
66]
C
ZB
Zero balance of the sensor element (unit mV/V, e.g. -0.0142 according to
calibration protocol)
8000:25 [
}
66]
E
max
Nominal load of the sensor element
8000:24 [
}
66]
A
S
Scaling factor (e.g. factor 1000 for rescaling from kg to g)
8000:27 [ } 66]
G Acceleration of gravity in m/s^2 (default: 9.80665 ms/s^2)
8000:26 [
}
66]
Gain
8000:21 [
}
66]
Tare
8000:22 [
}
66]
Conversion mode
The so–called conversion mode determines the speed and latency of the analog measurement in the
EP3356. The characteristics:
Mode Meaning typ. la-
tency typ. current
consumption
0 High precision
Analog conversion at 10.5 kSps
(samples per second) Slow conversion
and thus high accuracy
7,2 ms 70 %
(see Technical
data [ } 9] re-
garding nomi-
nal value)
1 High speed / low latency Analog
conversion at 105.5 kSps (samples per
second) Fast conversion with low latency
0,72 ms 100 %
(see Technical
data [
}
9] re-
garding nomi-
nal value)
Due to the conversion principle of the EP3356, the analog voltage is only available as a digital value after a
defined time. This is shown in figure below.
A step signal 0->1 is applied to the input. The measured value is reached and readable within the defined
accuracy after 7.2 ms or 0.72 ms, depending on the conversion mode 0/1. At this time the timestamp is also
acquired in Distributed Clocks mode. In real operation a step signal is not normally connected, but rather a
higher frequency but constant signal. The EP3356 then maps the input signal with the corresponding latency
for further processing, for which reason faster querying of the sampling unit at shorter intervals than the
latency (EP3356 allows up to 100 µs) makes sense for true-to-detail mapping of the analog input signal.