Features
- 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
The Sensoray Model 7430 Smart A/D offers a cost-effective way to acquire sensor data for any STD bus system. They feature 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 7430 board plugs directly into any STD bus slot. Channel linearization, calibration, and sensitivity are software- programmable, eliminating trim potentiometers and the need for board access.
Calibration
The 7430 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, RTD's, 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 RTD's, thermistors, and resistors are eliminated with the use of four-wire circuits.
The on-board microprocessor continually scans the active sensor channels. Each channel is scanned, amplified, digitized, filtered, converted to engineering units, and stored in on-board memory, independent of host CPU activity.
Field wiring is made directly to the 7430. Each channel has a 5-pin connector: two pins for voltage inputs, two for excitation, and a fifth pin for connecting a shield. A temperature sensor is attached to an integral isothermal plate as a thermocouple reference. These connectors are supplied with each 7430.
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 |
-25 to 85 °C |
| Interface |
STD 80 |
| Input power |
5 V (at 100 mA)
12 V (at 45 mA) |
| Dimensions |
(W x H): 4.50 x 6.70 inches |
| 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 types 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 |