EBRG bridge layer

The EBRG layer provides 16 channels of low level signal conditioning. It is designed primarily for use with bridge type transducers. This layer conditions each of the input signals by means of programmable excitation circuitry, an 8 pole Butterworth analog guard filter, programmable amplifier gain and offset, 16-bit analog to digital converter sampling at 100000 Hz in the Decimal domain (or 98304 Hz in the Binary domain) with simultaneous sampling for all 16 channels, selectable digital filters, and output sample rate achieved by means of multiple stages of combined down sampling / digital filtering.

The EBRG layer supports Full and Half bridge types with resistance ranges from 100 to 10000 Ohm, and Quarter bridges with resistance of either 120 or 350 Ohm (as a factory installed option). A set of internal shunt resistors (50, 100, 200, and 500 kOhm) is available for sensor scaling and test setup sanity checks. Other features include the following.

  1. Differential inputs provided for the analog input signals.
  2. Synchronous sampling with other EBRG, EHLS and EDIO layer channels.
  3. Flexible configuration option for filter type, low pass filter bandwidth, and sample rate on a per channel basis. FIR Linear Phase and FIR Butterworth 8P filters are available in the Decimal domain; only specialized FIR Butterworth 8P filters are available in the Binary domain.
  4. For EBRG layer models 02 and above, an optional analog output sub board is available to provide high level analog output signals for each channel.
  5. For EBRG layer models 02 and above, the excitation is provided on 4 channel Bank basis (i.e., the excitation voltage for Bank 1 [channels 1-4] can be selected independent of the excitation voltages selected for the other three (3) Banks).

The diagram shows the M8 connectors on the EBRG layer.

Each independent channel contains programmable excitation, an eight-pole Butterworth analog guard filter, a 16-bit A/D converter, software selectable digital filtering and output sample rate options of up to 100 kHz.

The EBRG layer supports full- and half-bridge types with a resistance from 100 to 10000 Ohms and quarter-bridges with a resistance of either 120 or 350 Ohms. All bridge configurations are accomplished using programmable switches , however, the quarter-bridge choice of 120- or 350-Ohm completion resistor is a factory installed option. A set of internal shunt resistors with selectable shunt direction is available for calibration purposes.

Wiring diagrams

EBRG Analog input

Use the Somat SAC-TRAN-MP Transducer Cable (1-SAC-TRAN-MP-2-2 or 1-SAC-TRAN-MP-10-2) to wire EBRG analog inputs.

NOTE
Do not use this wiring diagram for EHLS channels.

Strain gages

Piezoresistive transducers

Analog Output

The EBRG is available with an optional analog output function to provide high level analog output signal for each channel. Outputs are filtered analog output signals that can be used in the creation of time-domain lab durability tests. Each output channel is associated with the corresponding (like-numbered) input channel on the EBRG board. Connect the analog outputs to the EBRG through the Analog Output connector on the back panel shown in the diagram below.

This diagram shows the analog out connector on the back panel of an EBRG layer.

The outputs are generated from a D/A converter implemented as a unity gain follower to the A/D converter. The eDAQXR uses the non-inverting unity gain follower by default. Select the Analog output inversion option in the test setup configuration to use the inverting unity gain follower when the channel calibration slope is negative.

NOTE
The EBRG uses a nominal ±2-volt A/D converter. However, do not assume that the user-defined full-scale values are even approximately equivalent to ±2 volts for any particular channel. This is primarily because eDAQXR automatically provides a minimum over range protection of 1% and the eDAQXR can set gains only at certain discrete values resulting in actual over range protection that is sometimes significantly larger than 1%.