| Model

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; no external power supply is required.

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 eliminates several common sources of thermocouple measurement error. Its novel internal design eliminates module-induced thermal gradients, and a removable cover is provided to insulate thermocouple cold junctions from disruptive thermal transients.

Calibration

Fully electronic calibration is used to ensure rock-solid performance in high-vibration environments. Factory-programmed calibration data is stored in the module to enable quick and easy installation.

Sensor Connections

Robust, removable screw terminal blocks are provided for all field wire connections. 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)
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	03-01-24	PDF	645 KB
Model 2218 mechanical drawing	1.0.0	10-24-19	PDF	64 KB

Downloads

File	Version	Date M-D-Y	Type	Size
Windows software development kit	1.0.2	03-18-24	ZIP	37.29 MB
Linux software development kit	1.0.2	03-12-24	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.