DESCRIPTIONDP-cPCI-1197 is a high-resolution signal-conditioning module that amplifies the signals from full-bridge based transducers. This signal-conditioning module is available on a cPCI module form factor. This module has four gain settings to accommodate a wide variety of sensor output voltages. In addition, this module has an adjustable excitation voltage to accommodate transducer excitation requirements.

A high resolution sigma-delta ADC and variable gain amplifier forms the core of the signal conditioning system. Direct digital conversion and digital isolation ensures a better signal integrity in comparison with the conventional analog system.

The DP-cPCI-1197 is designed to acquire analog inputs in differential configuration. DP-cPCI-1197 board can acquire data from six differential analog field inputs with a maximum input range of +1V. The usable resolution of ±11mV at low gain in ±1V range and ±2mV at high gain in ±33.3mV range is available. This enables acquisition of abnormal out of range conditions.

DP-cPCI-1197 provides independent excitation for each channel. The voltage is selectable from 0V, 1V, 2V, 5V and 10V. To ensure the quality and stability of the excitation source, only the voltage levels ideally required for transducer excitation are provided.

Each channel includes a sensing circuitry that compensates for voltage variations due to cable and lead length. This sensing circuit ensures that set excitation voltage is maintained even with long cables.

The variable gain amplifier has both software and jumper programmability. Jumper programming selects high gain mode (10, 300) or low gain mode (1, 30). Software programming selects between the lower gain(1, 10) and higher gain (30, 300).

Each channel of DP-cPCI-1197 includes a dedicated high resolution sigma delta ADC. The input signals from the transducers are passed through a variable gain amplifier and an optional six-pole low pass filter for reach ADC inputs.

INPUT RANGE

EXCITATION

PROGRAMMABLE GAIN AMPLIFIER

CONVERSION AND DATA TRANSFER

KEY FEATURES AND BENEFITS

A

•Signal conditioning for full bridge based transducers

•Six wire measurement

•Programmable excitation voltages of 0, 1, 2, 5, 10 Volts

•Gain of 1, 30 (software selectable) and 10, 300 (jumper selectable)

•High resolution Analog to Digital conversion for each channel

•Direct digital interface to PXI backplane

•Digital isolation for excellent linearity

•Channel-to-Channel isolation

•Six pole low pass filter (Optional)

•Analog output (Optional)

•Memory 32K sample FIFO per channel

•Current Value Table

• Internal or external pacer

•PXI bus trigger or external trigger

•Built in self test

•Software shunt calibration

•Hardware window comparator with alarms and de-bounce

•Maximum and minimum peak value table for each channel

•DMA transfer for high data throughput

•Windows 2000 drivers provided

•RT Linux drivers provided

•High reliability signal conditioning and data acquisition for full bridge configuration sensors

•Safety critical systems

•Control systems

•Plant and process automation

PPLICATIONS

DP-cPCI-1197 6 Channel Signal Conditioner & Data Acquisition Module

for Full Bridge Transducers

14

DP-cPCI-1197

ISOLATION

SAMPLING AND STORAGE

WINDOW COMPARATORS

TRIGGERS AND PACERS

DMA DATA TRANSFER

CALIBRATION

OFFSET TARE

SHUNT CALIBRATION

DAC OUTPUTS

SOFTWARE CONTROLS

SOFTWARE SUPPORT

Each input channel is isolated from other channels and the system digitally using opto- couplers. The isolation voltage is 500 V DC.

The sampling rate of data in the ADC can be programmed between 6.9Hz and 3.5 KHz. The acquired data is stored in an on-board FIFO of 32K sample depth per channel. The stored data is acquired from the FIFO by the host computer. A Current Value Table (CVT) is provided. The latest acquired value can be read directly from the CVT, without affecting the FIFO. Simultaneous sampling of all channels in the board as well as all channels on the other similar boards in the same system can be carried out.

Upper and lower thresholds for alarm limit can be programmed for each channel. The alarms can be set with selected de-bounce time. Out of range interrupts as well as potential free alarm contacts are available for safety critical systems.

The channels can be triggered through the software. PXI trigger is available from the backplane. External hardware trigger is also available. Internal and external pacers are provided. Hardware internal pacer is common to all channels, but individual pacers can be set to individual channels through software. Common pacer to all channels can also be set to all channels through software.

The module supports Scalter / Gater DMA and it enables to transfer the data from on board buffers to system memory without the overhead of software. This helps to high speed data acquisition / storage rates.

The Modules are calibrated at factory to read the input signal accurately. The calibration values are stored in an on-board EEPROM. The driver software uses the calibration constants to enhance the system measurement accuracy.

DP-cPCI-1197 is built over a high resolution ADC. This feature is utilized for the null compensation. The high resolution of ADC allows the tare compensation to be implemented in the software. The output at NULL state is read and stored. This value is used to calculate the actual pressure / strain values. DP-cPCI-1197 can be used to tare up to 87.5% of the Full-scale with the same resolution of 16-bit systems. Digital offset tare ensures very low drift because it eliminates DACs and analog summing junctions which contribute to drift.

On-board shunt calibration is provided on each channel. One shunt calibration point is available. The shunt is enabled under software control. This mechanism enables a complete self-test. The field wiring and the transducer full bridge is simulated in the self test

Parallel analog outputs via DACs are optionally available. Optional adapter board is available for the real time signal conditioned data to be simultaneously recorded on external analog recording systems. This parallel recording will be proved even under conditions of software hanging due to all hardware architectures.

Software controls have been given to most parameters. These include Input voltage range, excitation voltages, tare, shunt calibration and sampling rate.

The module is supplied complete with device drivers in Windows 2000 and RT Linux. Please contact factory for support in any other operating system such as VxWorks, QNX, INTime, Lynx etc.

15

D

DP-cPCI-1197

INPUT

VOLTAGE RANGE AND ACCURACY

GAIN ACCURACY

CONVERSION CHARACTERISTICS

STABILITY

No. of Channels 6 differential input channelsInput Impedance >10MWInput Coupling DCOver Voltage Protection ±25VAbsolute Maximum working Voltage ±10 V of respective groundShunt Calibration 1 shunt for each channelSystem Course Balancing 100% of measurement range

Gain Range Resolution Accuracy 1 ±1V ±11µV +0.05%

30 ±33.33mV ±2µV +0.05%

High Bandwidth (100Hz, 1KHz) 0.05%(with calibration)

Sampling Rate* Programmable up to3.5KSa/S/ch

Noise ±1µV @ 6.9 Hz±80µV @ 3.5 KHz

Recommended Warm-up time 30 Minuteso Offset Temperature co-efficient ±0.9 mV / C oGain Temperature co-efficient ±10ppm / Co Offset Temperature co-efficient ±0.9 mV / C oGain Temperature co-efficient ±10ppm / C

SPECIFICATIONS

EXCITATION CHARACTERISTICS

DYNAMIC CHARACTERISTICS

MECHANICAL

CONNECTOR

ENVIRONMENT

ORDERING INFORMATION

Channels 6 Independent channelsVoltage 0, 1, 2, 5, 10V DC software SelectableAccuracy ±5mVDrift ± 10ppmCurrent 50mA per channel

NMRR 70 dB @ 50 Hz, 6.9 Hz samplingCMRR 100dB

Board 6U 233.35 mm X 160mm

Field Interface 68 pin SCSISystem Interface cPCI/PXI J1 & J2 connector

Commercial version only

DP cPCI 1197 3 0 0

0 - Without output DAC 3 - With output DAC

3 - Commercial version

Factory options specified based on applications

16

BLOCK DIAGRAM OF DP-cPCI-1197

Channel 6

Channel 2

Channel 1

CHANNEL 6

CHANNEL 2

CHANNEL 1

Excitation

Buffering & Lead Compensation

Excitation

Selection

Ref. Voltage &

Supply Generation

DC-DC Converter

+12V

-12V

V

F1

c

P C

I

C O

N N

E C T O R

VGA 24Bit

ADC

F1

Optocoupler

c

P C

I

I N T

E R

F A

C E

Gain 1, 10, 30, 300

Relay Alarm

Ch. No., Gain, Exc. Voltage

Tag Register

Window

Comparator

MUX

Control Logic

DMA Data Transfer

CH1

ADC

DIGITAL LOGIC INTERFACE

F

I E

L D

C

O N

N E

C T O R

S+

E+

E-

S-

CVT

Min-Max

Value Table

+15

-15

Output DAC

Data Merging

Channel

Data

128K Sample FIFO for

Ch 1 - 4

64K Sample FIFO for Ch 5 - 6

6 Channel