USB compatible 8-channel sensor interface | Model 2218
- Measures thermocouples, RTDs, thermistors, voltage and resistance
- Provides complete sensor signal conditioning
- High-accuracy differential inputs
- Excellent 50/60 Hz rejection
- Pulsed excitation minimizes sensor self-heating
- 4-wire circuits eliminate lead-loss errors
- 8 GPIOs with input debounce and edge detection
- Powered by USB
Description
Model 2218 is a USB-compatible module that interfaces eight sensors to a host computer. It provides excitation for passive sensors and complete signal conditioning for thermocouples, RTDs, thermistors, and strain and pressure gauges. Each channel can be independently configured to measure voltage, resistance, or any supported sensor type. In addition, eight independent digital I/O lines (3.3 V logic) are available for general-purpose use. All GPIOs support edge detection, programmable direction and software-configurable pull-up/pull-down control. The module is USB-powered. An auxiliary 5V jack is provided for use with high current sensors.
2218 block diagram
The module automatically scans the eight sensor channels and produces up to five samples/second per channel. When scanned, a sensor is excited, cold-junction compensated, amplified, digitized, and linearized as required by the sensor type. Samples are automatically converted to appropriate engineering units (e.g., °C, Ω, and V) and sent over USB at a programmable rate so that the host computer never needs to initiate or wait for data conversion.
Smart excitation
Sensoray's exclusive pulsed excitation system provides the ideal stimulus for passive sensors. Excitation is applied only when measuring, thus reducing both sensor self-heating and overall module power consumption. The excitation type and level is automatically reconfigured, on-the-fly, for each channel to optimize sensor stimulation.
Lossless measurement
Each channel has provision for a four-wire connection, enabling it to completely eliminate lead loss errors from RTD, thermistor, and resistor measurements.
Accurate thermocouples
The module implements a novel internal design which minimizes thermal gradients at the thermocouple cold junctions.
Calibration
The 2218 has hardware that on-board CPU uses as reference standards for periodic re-calibration to maintain high accuracy without interrupting data capture. Fully electronic calibration is used to ensure rock-solid performance in high-vibration environments. Default factory-programmed calibration data is stored in the module to enable quick and easy installation.
Sensor Connections
Spring-lock type pluggable terminal blocks are provided for all field wire connections ensuring long term reliability. Analog signals connect to a cluster of four terminal blocks along one side of the module; digital signals connect to a single terminal block on the opposite side.
Specifications
| Sensor channels | |
|---|---|
| Number of channels | 8 |
| Interface | 4-wire (2 excitation, 2 analog input) |
| Input voltage range | Normal operation: ±5 V Absolute max: ±20 V |
| Scan rate (per channel) | Up to 5 samples/s |
| Input impedance | 1000 MΩ |
| CMRR | 78 db @ 0-60 Hz, min |
| CMV range | ±5V |
| Supported sensors | |
| Thermocouple | J, K, T, S, E, B, N, C, R |
| RTD |
Pt 100 α = 385 Pt 100 α = 392 Ni 200 α = 1.098 Ni 1000 α = 4.4 Cu 10 α = 0.039 |
| Thermistor | 10 KΩ types 44006 / 44031 |
| Voltage ranges | ±5 V ±500 mV ±100 mV |
| Resistance ranges | 0 to 400 Ω 0 to 4 KΩ 0 to 600 KΩ |
| Digital I/Os | |
| Number of I/Os | 8 |
| Interface | 3.3 V CMOS logic |
| Programmable functions | Edge detection, direction, pull-up/down configuration |
| System | |
| Interface | USB 2.0 high-speed |
| Input power | USB powered, 1.75 W (350 mA @ 5 VDC) |
| Auxiliary power | 5 VDC +- 5% |
| Operating temperature | 0 to 70 °C |
| Storage temperature | -25 to 85 °C |
Documentation
| File | Version | Date M-D-Y | Type | Size |
|---|---|---|---|---|
| Manuals | ||||
| Model 2218 technical manual Hardware and API documentation | 1.0.1 | 10-17-24 | 645 KB | |
| Model 2218 mechanical drawing | 1.0.0 | 05-16-25 | 88 KB | |
| Application Notes | ||||
| Labview: Making your own VIs | — | — | HTML | — |
| Matlab: Application notes | — | — | HTML | — |
Downloads
| File | Version | Date M-D-Y | Type | Size |
|---|---|---|---|---|
| Windows software development kit | 1.0.3 | 05-09-25 | ZIP | 37.28 MB |
| Linux software development kit | 1.0.2 | 10-17-24 | BZ2 | 398 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. | ||||