8-channel smart sensor interface | Model 118
- 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
Model 118 is obsolete. This archived information is provided as a courtesy to customers who own model 118 units.
Description
Model 118 is an 8-channel Smart A/D that offers a cost-effective way to acquire sensor data for any VME 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.
An on-board microcontroller continually scans the sensor channels. Each channel is amplified, digitized, filtered, linearized, converted to engineering units, and stored in on-board memory so it can be instantly read by the host. Signal conditioning is provided for thermistors, RTD's, strain and pressure gauges, and resistance measurements. Standard corrections for non-linear sensors is built in.
A pulsed excitation source is provided for passive resistive sensors to minimize sensor self-heating. Lead loss errors from RTD's, thermistors, and resistors are eliminated with the use of four-wire circuits.
The board periodically samples internal reference standards and uses the sample data to correct offset and gain errors. Factory-calibration data is stored in an EEPROM so that boards may be easily interchanged. Calibration is fully electronic, thereby eliminating trimpots and the need for board access during recalibration.
The 118 board is available with 3U and 6U front panels. Sensor field wiring is accomplished with a 40-conductor flat cable and a remotely mountable screw-termination board.
Example application using external 7409TB breakout board
Specifications
| Input resistance | 100 MΩ |
| Maximum input voltage | 63 VAC rms |
| CMRR | 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 |
| VME interface | A16, D8 |
| Input power | 5 V (at 100 mA)
12 V (at 35 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 | 10 KΩ, YSI type 44006 or 44031 |
| Strain gauges | 120 to 4000 Ω |
| Thermocouples | 0.1 °C | °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 118 Instruction Manual | 1.0.0 | 10-17-24 | 304 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. | ||||