Model 518 | 8-Channel Smart Sensor Interface

Model 518 8-Channel Smart Sensor Interface
  • Measures thermocouples, RTDs, strain gauges, thermistors, voltage and resistance
  • 8 high-accuracy differential sensor inputs
  • Dynamically reconfigurable, pulsed sensor excitation system
  • Supports 4-wire circuits to eliminate lead-loss errors
  • Fully electronic calibration
  • Low power

Description

Model 518 is an advanced, eight-channel sensor measurement system on a PC/104 board. It generates excitation for passive sensors and provides complete signal conditioning for thermocouples, RTDs, thermistors, and strain and pressure gauges. Each channel can be individually configured to measure voltage, resistance, or any supported sensor type.

Model 518 block diagram

518_diag_sysblock.jpg

The board continuously scans all enabled sensor channels at a 45 channels/second rate. When scanned, each sensor is excited, amplified, digitized, filtered, linearized, converted to engineering units (e.g., °C, Ω, V), and stored in on-board memory, independent of host CPU activity. The host can quickly retrieve the most recent sample from each channel so that it never needs to initiate or wait for data conversion.

Fully electronic calibration is used, thereby preventing calibration loss due to board vibration. Factory calibration data is stored onboard so that model 518 boards can be easily and quickly installed.

Excitation

Sensoray's exclusive pulsed excitation system provides stimulus for passive sensors. Pulsed excitation reduces sensor self-heating and it also helps to lower the board's overall power consumption.

The excitation system is dynamically reconfigurable; its circuit topology changes as needed to adapt to the type of sensor being measured. For example, a pulsed constant voltage is applied to strain and pressure sensors, whereas pulsed constant current is applied to passive resistive sensors such as RTDs.

Each channel has provision for a four-wire sensor connection that eliminates lead loss errors from RTD, thermistor, and resistor measurements.

Thermocouples

Thermocouples are widely used in industrial measurement and control applications because of their relatively low cost and wide temperature ranges. In particular, thermocouples excel at measuring high temperatures where other common sensor types cannot function.

Model 518 includes support for an external cold junction compensation (CJC) sensor, which is required for thermocouple measurements. A CJC sensor is built into several of Sensoray's 518-compatible termination boards. The CJC sensor is measured by a dedicated analog input channel so that the eight sensor channels always remain available for application use.

Sensor Connections

All field wiring signals are accessible through a 40-pin header. The header may be connected to a custom termination system or to any of several breakout boards available from Sensoray.

Typical Application

518_app.gif

Accessories

Sensoray offers several solutions for connecting model 518 to field wiring. All of the products shown below can be connected to the 518's I/O header with either of two 40-conductor flat cables, models 7409C (18") or 7409C1 (1M).


Model 7409TB is a compact board that breaks out all of the 518's I/O signals to screw terminals. It includes a thermocouple compensation sensor that automatically connects to the 518's CJC input. Thermocouples and other sensors may be directly connected to the 7409TB. For best results with thermocouples, the 7409TB should be insulated from air flows.

7409TB — compact breakout board with TC compensation sensor

7409TB breakout board


Model 7409TDIN is a DIN rail mountable board that breaks out all of the 518's I/O signals to removable screw terminal blocks. It includes a generous prototyping area, and a thermocouple compensation sensor that automatically connects to the 518's CJC input. Thermocouples and other sensors may be directly connected to the 7409TDIN. For best results with thermocouples, the 7409TDIN should be insulated from air flows.

7409TC — DIN rail mountable breakout board with TC compensation sensor and prototyping area

7409TC breakout board


Model 7506TDIN is a DIN rail mountable board that breaks out all of the 518's I/O signals to screw terminals. It does not have a thermocouple compensation sensor, though an external TC compensation sensor may be connected to the appropriate screw terminals if it will be used with thermocouples.

7506TDIN — DIN rail mountable breakout board

7506TDIN breakout board

Specifications

Analog Inputs
Sensor channels 8
Input voltage range Normal operation: ±5 V
Absolute max: 63 VAC rms, applied for up to 2 seconds
A/D converter 16-bit integrating
Conversion time 22 mS per channel
A/D scan rate 45 samples/second
Input impedance 1000 MΩ
CMRR 95 db, min
CMV ±5V, max
Power and Environmental
Input power +5 V @ 100 mA
-12 V @ 35 mA
+12 V @ 45 mA
Operating temperature -25 to 85°C
Supported Sensors
Thermocouple J, K, T, S, E, B, N, C, R
RTD Platinum: 100 ohms, types 385 and 392
Nickel: 120 Ω, 200 Ω, 1000 Ω
Copper: 10 ohms
Thermistor 10 KΩ, YSI type 44006 or 44031
Strain gage 120 to 4000 Ω

Documentation

File Version Type Size
Manuals
Model 518 Technical Manual1.0.0PDF280 KB
Application Notes
Model 518 tech support wiki
FAQs, examples and additional information
HTML
Other
Model 518 Mechanical Drawing1.0.0PDF22 KB

Downloads

File Version Type Size
Smart A/D Software Development Kit
Latest for Windows 7
1.1.0ZIP10.13 MB
Smart A/D Software Development Kit
Legacy for Win2000 & XP
1.0.2ZIP243 KB
Other Operating Systems
Need a software development kit for another operating system? We can port our SDK to
your OS or provide the information you need to do it yourself. Contact Sales for details.

Pricing & Ordering

Model Description Qty 1 Qty 2-9 Order Qty.
5188-Channel Smart Sensor Interface$333$303
Termination Breakout Boards
7409TBBreakout Board, 40-pin, with CJ Sensor$67$61
7409TCBreakout Board, 40-pin, with CJ Sensor and Prototype Area, Panel Mountable$106$96
7409TDINBreakout Board, 40-pin, with CJ Sensor and Prototype Area, DIN mountable$141$126
7506TDINBreakout board, 40-pin, DIN rail mountable$80$73
Cables
7409CCable, flat, 40 conductor, 18 inches$20$19
7409C1Cable, flat, 40 conductor, 1 meter$29$26

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