8-channel low power smart sensor interface | Model 7429
- 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Model 7429 is obsolete. This archived information is provided as a courtesy to customers who own model 7429 units.
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
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 resistance | 100 MΩ |
| Maximum input voltage | 63 VAC rms |
| CMMR | 95 db/min |
| Maximum command mode | ±5 V |
| A/D converter | 16-bit integrating |
| Conversion time | 22 ms/channel |
| A/D scan rate | 45 samples/second |
| Operating temperature | -40 to 85 °C |
| Interface | STD 80 |
| Input power | 5 V (at 100 mA)
12 V (at 45 mA) |
| Sensor Types | |
|---|---|
| Thermocouples | J, K, T, S, E, B, N, C, R |
| Platinum RTD | 100 Ω, types 385 and 392 |
| Nickel RTD | 120, 200, 1000 Ω |
| Copper | 10 Ω |
| Thermistors | 10000 Ω, YSI type 44006 or 44031 |
| Strain gauges | 120 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 | Date M-D-Y | Type | Size |
|---|---|---|---|---|
| Model 7429 Technical Manual | 1.0.0 | 10-17-24 | 131 KB | |
| Smart A/D Software Manual | 1.0.0 | 10-17-24 | 129 KB |
Downloads
| File | Version | Date M-D-Y | Type | Size |
|---|---|---|---|---|
| Smart A/D Software Development Kit | 1.0.2 | 10-17-24 | ZIP | 243 KB |
| Other Operating Systems | ||||
| Need a software development kit for another operating system? We can port our SDK to your OS for a NRE fee or, with a volume commitment, at no additional cost. Contact Sales for details. | ||||