8-channel low power smart sensor interface | Model 7429

Model 7429 8-channel low power smart sensor interface
  • Measures thermocouple, RTD, strain gage, voltage, 4-20 mA, thermistor, and resistance
  • 8 sensor channels with differential inputs
  • Provides excitation to passive sensors
  • Pulsed sensor excitation minimizes sensor self-heating
  • Cold-junction compensation for thermocouples
  • Each channel configurable for any supported sensor type
  • Fully electronic calibration
  • Ultra low power

Model 7429 is a legacy product and is not recommended for new designs. Legacy products are available but may have lead times up to 12 weeks and minimum order requirements. Use our Product Finder to find a comparable product or contact our Design Support Team.

Description

The Sensoray Model 7429 Smart A/D offers a cost-effective way to acquire sensor data for any STD bus system. It features 16-bit resolution from eight input channels, each individually programmable for a different sensor type. Analog-to-digital conversion is performed in under 22 milliseconds, providing a 45 channel per second scan rate.

The 7429 board plugs directly into any STD bus slot. Linearization, calibration, and sensitivity are software programmable, eliminating trim potentiometers and the need for board access. Sensor field wiring is accomplished with a 40-conductor flat cable and remotely mountable screw-termination board, either Model 7409TB or Model 7409DIN with DIN rail mounting hardware.

Model 7429 Application

7429_app.jpg

Calibration

The 7429 automatically self-calibrates by measuring internal references. Reference data is stored in an EEPROM so that boards may be easily interchanged. Signal conditioning is provided for thermistors, RTDs, thermocouples, strain and pressure, resistance and voltage inputs. Standard correction for non-linear sensors is built in. Custom compensation can be downloaded.

Excitation

A pulsed constant-voltage source is provided for strain and pressure sensors. A pulsed constant-current source is provided for resistive sensors. Lead loss errors from RTDs, thermistors, and resistors are eliminated with the use of four-wire circuits. An on-board microprocessor continually scans the active sensor channels. Each channel is amplified, digitized, filtered, converted to engineering units, and stored in on-board memory independent of host CPU activity.

Low power mode

In the "awake" mode, power dissipation is just 650 mW. Sending a powerdown command puts the board in a low power standby state. The board is awakened by a software command.

Extended temperature

The use of integrated circuits rated at -40 to 85 °C or better allows the 7429 to operate down to -40 °C.

Specifications

Input resistance100 MΩ
Maximum input voltage63 VAC rms
CMMR95 db/min
Maximum command mode±5 V
A/D converter16-bit integrating
Conversion time22 ms/channel
A/D scan rate45 samples/second
Operating temperature-40 to 85 °C
InterfaceSTD 80
Input power5 V (at 100 mA)
12 V (at 45 mA)
Sensor Types
ThermocouplesJ, K, T, S, E, B, N, C, R
Platinum RTD100 Ω, types 385 and 392
Nickel RTD120, 200, 1000 Ω
Copper10 Ω
Thermistors10000 Ω, YSI type 44006 or 44031
Strain gauges120 to 4000 Ω
Sensor Resolution Range
Thermocouples 0.1 °C -270 to 1760 °C
Thermistors 0.01 °C -55 to 145 °C
Resistors 0.02 Ω
0.125 Ω
31 Ω
0 to 400 Ω
0 to 3 kΩ
0 to 600 kΩ
RTDs 0.05 °C
0.0125 °C
-200 to 800 °C
0 to 400 °C
Strain/pressure 5 µV ±100 mV
DC voltage 5 µV
20 µV
200 µV
±100 mV
±500 mV
±5 V

Documentation

File Version Type Size
Model 7429 Technical Manual1.0.0PDF131 KB
Smart A/D Software Manual1.0.0PDF129 KB

Downloads

File Version Type Size
Smart A/D Software Development Kit1.0.2ZIP243 KB
Other Operating Systems
Need a software development kit for another operating system? We can port our SDK to
your OS or provide the information you need to do it yourself. Contact Sales for details.

Pricing & Ordering

Model Description Qty 1 Qty 2-9 Order Qty.
74298-channel low power smart sensor interfaceCallCall 
Termination boards
7409TBBreakout board, 40-pin, with temperature sensor$72$65
7409TCBreakout board, 40-pin, with temperature sensor and prototyping area$113$103
7409TDINBreakout Board, 40-pin, with temperature sensor and prototype area, DIN mountable$151$135
Cables
7409CCable, flat, 40 conductor, 18 inches$21$20
7409C1Cable, flat, 40 conductor, 1 meter$31$28

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