Description
This documentation covers the following device descriptions
- EL3751-0000 multifunctional terminal
- EL3751-0020 like EL3751-0000, additionally with Beckhoff factory calibration certificate
- EL3751-0004 reduced to resistance measurement variant of EL3751‑0000 for resistance measurement up to 5 kΩ and RTD-based (temperature) measurement, technical features there like EL3751‑0000
- EL3751-0024 like EL3751‑0004, additionally with Beckhoff factory calibration certificate
As a multi-functional input for analog measurement technology, the EL3751‑0000 analog input terminal can be used for measuring electrical parameters in several measuring ranges. The respective nominal measuring ranges are:
- Voltage between ±5 mV and ±30 V, 0..10 V, 0..5 V
- Current in the range ±20 mA , 4..20 mA, 0..20 mA, NAMUR NE43
- Resistor bridge, strain gauge (SG): 1/4 bridge (350 Ω + 120 Ω),
1/2 bridge (±16 mV/V) and 1/1 bridge (±32 mV/V) in 2-6 wire connection - Electrical resistance R / temperature with RTD (PT100 etc.): 0…5 kΩ in 2-4 wire connection
- Potentiometer up to 1 kΩ
The nominal measuring range referred to above is part of the total available and usable technical measuring range, which for the EL3751 is approx. ±107%, depending on the measuring range. The "extended range" property can be disabled, in order to make the behavior compatible with the EL30/31/36xx "legacy range".
The measurement takes place via a differential input channel. It is digitized with a resolution of 24 bit and 10 ksps and transported electrically isolated from the fieldbus to the higher-level automation device with optional oversampling. The integrated supply and the switchable auxiliary resistors enable direct connection of a resistor bridge (strain gauge SG) or load cell with 2-/3-/4-/6-wire connection technology, a fixed resistor, a PTC or a potentiometer. The signal state of the EtherCAT Terminal is indicated by light emitting diodes.
If a lower sampling rate is required, a data rate reduction (referred to as decimation) can be set internally, based on the fixed analog sampling rate of 10 ksps. The sampling rate of ≤ 10 ksps achieved in this way can then be transferred to the controller via EtherCAT, based on the task cycle time and a suitable oversampling factor.
The terminal has two configurable numeric software filters up to FIR 39th order (40 taps) or IIR 6th order. The first filter is applied to the 10 ksps raw data, the second filter is based on the user-settable decimation, with a view to suppressing aliasing effects. Both filters can be set based on an integrated list (a number of low-pass, high-pass, mean value filters) or a freely selectable coefficient table.
Non-linear characteristic sensor curves can be corrected flexibly through an integrated sampling points table. Simple mathematical operations are also possible.
Each terminal has a unique ID number, which is printed and electronically readable. The optionally available factory calibration certificate (EL3751-0020, EL3751-0024) can be assigned via this ID number; re-calibration is possible.