Oversampling Terminals/Boxes And Twincat Scope - Beckhoff EL3783 Documentation

three-phase, 3-conductor grid, not earthed
U
L-L
66 V
115 V
120 V
127 V
200 V
220 V
230 V
240 V
260 V
277 V
347 V
380 V
400 V
415 V
440 V
480 V
500 V
577 V
600 V*
*) maximum rated voltage of the grid
Technical data
All technical specifications apply to "3-phase, 4-conductor system with earthed neutral conductor"
unless explicitly stated otherwise (see also Examples of measurement methods [} 39]).
Changes in the CoE directory
In case of changes to the CoE default parameters, it is essential that corresponding values are en-
tered in the start-up list, so that in the case of exchange the EL3783 operates again as foreseen in
the application.
5.4

Oversampling terminals/boxes and TwinCAT Scope

Generally input data of a terminal/box could be achieved by the scope either directly (via the activated ADS
server) or by creation of a PLC variable which is linked to the PDO of a terminal/box for recording them. Both
procedures will be explained for TwinCAT 3 (TC3) at first and for TwinCAT 2 (TC2) respectively.
Oversampling means that an analog or digital input device supplies not only one measured value for each
process data cycle/EtherCAT cycle (duration T), but several, which are determined at a constant interval
t < T. The ratio T/t is the oversampling factor n.
A channel thus offers not only one PDO for linking in the process data, as in the example here with the
EL3102, but n PDOs as in the case of the EL3702 and other oversampling terminals/boxes.
The definition of "oversampling" by the Beckhoff's point of view shouldn't be mixed up with the oversampling
process of a deltaSigma ADC:
• deltaSigma ADC: the frequency used by the ADC to sample the analogue signal is faster than a
multiple times than the frequency of the provided digital data (typically in kHz range). This is called
oversampling resulting by the functional principle of this converter type and serve amongst others for
anti-aliasing.
• Beckhoff: the device/ the terminal/box read of the used ADC (could be a deltaSigma ADC also) digital
sample data n-times more than the PLC/ bus cycle time is set and transfers every sample to the control
– bundled as an oversampling PDO package.
For example these both procedures are arranged sequentially by their technical implementation within the
EL3751 and can also be present simultaneously.
EL3783 Version: 1.1
Commissioning
111