TDAS PRO
Sensor Input Module (SIM)

Each TDAS PRO Sensor Input Module (SIM) is a standalone, eight-channel data acquisition system.

Communication Method
TDAS PRO equipment supports the industry-standard Ethernet 10BaseT communication method.

Input Range
The nominal sensor input range is ±5.0 volts at a gain of 1. Voltages up to ±6.25 volts may be recorded when channel gain is set to 0.8. Common-mode range is …±7.0 volts.

Excitation Sources
The excitation source for each channel is individually controlled and isolated. Excitation sources are not turned on until the software initializes the system during the Real-Time or Collect Data modes. TDAS Control software allows one of two excitation voltages to be selected for each channel.

Sensor Connectors
DTS supplies TDAS PRO SIMs with a variety of connectors, including 0B, 1B, 2B LEMO and Tajimi.

Shunt Calibration Resistors
Each TDAS PRO SIM contains seven 0.1%, 25 ppm shunt calibration resistors. These resistors are connected between (+) excitation and (+) signal under software control.

Shunt Emulation
TDAS PRO SIM contains a shunt emulation circuit, effectively eliminating the need for conventional shunt resistors to perform shunt checks. When "Emulation" is chosen as the shunt calibration method within the TDAS Control software, the software injects a precisely calculated current into the sensor to create an expected deflection of the sensor's output. This current, or voltage source, is a digital-to-analog converter (DAC) that allows the shunt emulation circuit to function as a shunt resistor. DAC settings are automatically calculated by the software to simulate 70-80% of the full scale of the analog-to-digital converter.

Bridge Completion
Bridge completion may be software selected. When chosen, a precision half-bridge is connected across (+) excitation, (-) excitation and (+) signal. Therefore, half-bridge transducers should be connected to (±) excitation and (-) signal. The value of bridge completion resistors is 1,000 ohms.

Hardware Filters
Each TDAS PRO SIM measurement channel has an 8-pole Butterworth anti-aliasing filter with a fixed (-3 dB) knee point. There are 3 knee point options available: 4300 Hz, 2900 Hz, or 3000 Hz. Each channel also has a software-controlled, variable five-pole Butterworth filter for lower sampling rates. The TDAS Control Software automatically chooses the best filter setting for a chosen sampling rate.

Sensor ID
Each TDAS PRO SIM measurement channel supports communication with silicon serial number devices manufactured by Dallas Semiconductor/Maxim Integrated Products. When you connect an ID chip to the proper pins on the sensor connector, the TDAS Control software can automatically read these devices and correlate the serial number to channel set-up information.

Memory Size
TDAS PRO SIMs have 16 MB of non-volatile RAM. Each data sample occupies 2 bytes, therefore each 16 MB SIM can store up to 8 million samples. This memory is flexibly allocated. In general, the number of samples is the product of sample rate (Hz), sample size (seconds) and the number of channels in use.

Shock Rating
All TDAS PRO systems are rated for and tested to 100 g, 12 msec duration, in all axes. TDAS PRO equipment can be mounted directly on a vehicle, sled or other dynamic testing device.

Temperature Rating
Each is tested for full functionality with a case temperature of 70çC.