Description

The ELM3xxx series analog input terminals can be used for measuring electrical parameters in several measuring ranges. They forward the measured values to the controller via the EtherCAT fieldbus.
The covered measuring ranges are currently:

• voltage, bipolar ±20 mV … ±1200 V, unipolar 0…5 V, 0…10 V, 0…20 V,
• thereby, together with the detection of the cold junction, temperature measurement with thermocouples (TC) and thermocouple calculation (type K, E, T, …),
• current in the ranges ±20 mA , 4…20 mA, 0…20 mA, fault indication based on NAMUR NE43,
• resistor bridge, strain gauge (SG) with 2 to 6‑wire connection up to 32 mV/V:
• 1/4 bridge (quarter bridge, 2 to 3-wire connection), 1000 Ω, 350 Ω, 120 Ω,
• 1/2 bridge (half bridge, 3 to 5-wire connection) and
• 1/1 bridge (full bridge, 4 to 6-wire connection),
• electrical resistance R: 0…100 kΩ in 2 to 4‑wire connection in various measuring ranges depending on the device,
• as a result, also temperature with RTD conversion in the corresponding resistance range (Pt100, Pt1000, …),
• potentiometer,
• vibration sensors with current feeding in compliance with the IEPE standard (with charge output on request) and
• LVDT/carrier frequency on request, see also EL5072 optionally.

The majority of the terminals have non-electrically isolated channels, as this is generally not necessary in the 24 V machine environment and would only increase the device costs unnecessarily. In turn, individual devices such as the ELM3702-0101 have electrically isolated channels and are thus ideally suited for signals that have different potentials.

The measurement terminals are currently divided into two series

• ELM3x0x – the basic series (refer to the terminal specification for the specific properties)
• This is the universal device class for dynamic (fast) applications
• Max. sampling rates per channel: 10,000 to 50,000 sps
• Simultaneous sampling of the channels in the terminal (measure channels at the same time)
• In general, basic accuracy of 100 ppm_FSV @ 23°C
• ELM3x4x – the economy series (refer to the terminal specification for the specific properties)
• This is the most cost-effective device class for multi-channel applications and slowly changing signals
• Max. sampling rates per channel: up to 1,000 sps
• Multiplex sampling of the channels in the terminal (in succession)
• In general, basic accuracy of 100 ppm_FSV @ 10...40°C
• Simple self-supply through 24 V power contacts and connection for 24 V sensor power supply

Two supplementary families are available in addition to this:

• System components EKM1101, ELM9410
• The EKM1101 EtherCAT Coupler and the ELM9410 power supply terminal are comparable to the standard components EK1101 or EL9410 respectively in terms of operation, but they also offer
  - extensive real-time diagnostics: incoming/outgoing voltages and currents, temperature, vibrations, etc.
  - electrical isolation of E bus and power contact supply for interference-free measurement
• They can be used as supplements to the ELM3xxx terminals if their properties provide an advantage, but there is no obligation to do so. ELM3xxx terminals can also be used with standard couplers and the EL9410. Accordingly, EKM1101/ELM9410 can also be used on standard EL/ES terminals.
• Specific properties: see documentation for the system components

• ELM2xxx signal switch for metrological requirements
• With the ELM26xx and ELM27xx terminals, several high-quality electronic switches for analog signals are available, e.g. to implement multiplex applications.
• The ELM26xx are equipped with reed relays, and the ELM27xx have semiconductor switches (MosFET, solid state). For application notes and technical data, see the relevant documentation.
• Analog signals can also be routed with other switches such as EL2xxx.

The name key for the ELM3xxx terminals is as follows

ELM3abc-defg

The devices have several technical features that facilitate measurement taking. Availability depends on the device and series; please refer to the specific documentation.

• The channels of a device function independently as regards and can be parameterized separately.
• Various pluggable connection levels are offered ex-factory; currently, for the ELM3xxx, these include BNC, PushIn and LEMO and IEC thermocouple connectors.
• An analog channel can measure beyond the nominal range specified above. This simplifies commissioning and troubleshooting. The resulting technical measuring range is approx. 107% of the nominal range. The "extended range" property of the measuring range can be disabled in order to make the behavior compatible with the EL30/31/36xx series as a "legacy range".
• The devices described here all work with 24-bit analog resolution. The data transfer is performed in compliance with the IEC via 32-bit (4-byte) variables which must be taken into consideration for busload calculations.
  A reduced resolution of 8 or 16 bits can be set for some devices.
• Each channel operates with EtherCAT Distributed Clocks. Each measured value therefore has a specific timestamp with ns resolution.
• There are devices which perform a singular function, e.g. only voltage measurement, and also multi-functional terminals, which support several or all of the measuring ranges listed above.
• The singular function devices also offer high flexibility as regards the measuring range, for example the ELM35xx for strain gauges/weighing applications. 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/NTC element or a potentiometer.
• The channels operate at a fixed sampling rate, which is currently 1,000 to 50,000 sps (samples per second) depending on the device. If a lower rate is required in the application, each channel can decimate independently and be varied during runtime.
• Hardware filtering is designed for the usual ‑3 dB point to avoid aliasing.
• Each channel has two configurable numeric software filters up to FIR 39th order (40 taps) or IIR 6th order. 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. The filter design can be created with the TwinCAT Filter Designer or common tools (Matlab®, Octave), instructions can be found here in the document.
• Non-linear characteristic sensor curves can be corrected flexibly through an integrated sampling points table. Simple mathematical operations are also possible.
• Sensor commissioning is facilitated by the Auto Scale function at two measuring points.
• Each device has a unique ID number, which is printed and electronically readable (BIC/BTN).
• Calibration certificates can be created for some the devices as an option to order, provided in the form of a Beckhoff factory calibration certificate or an external calibration certificate in accordance with ISO 17025 or DAkks. Re-calibration can be carried out by Beckhoff service. Details on this are available from the Beckhoff sales team.

The individual devices are presented below.