National instruments simultaneous analog input module operating instructions and specifications (35 pages)
Summary of Contents for National Instruments Module SCXI-1503
Page 1
SCXI SCXI-1503 User Manual March 2007 374271A-01...
Page 2
Thailand 662 278 6777, Turkey 90 212 279 3031, United Kingdom 44 (0) 1635 523545 For further support information, refer to the Technical Support Information document. To comment on National Instruments documentation, refer to the National Instruments Web site at and enter the info code ni.com/info...
The reader should consult National Instruments if errors are suspected. In no event shall National Instruments be liable for any damages arising out of or related to this document or the information contained in it.
Page 4
Conventions The following conventions are used in this manual: <> Angle brackets that contain numbers separated by an ellipsis represent a range of values associated with a bit or signal name—for example, P0.<3..0>. » The » symbol leads you through nested menu items and dialog box options to a final action.
Contents Chapter 1 About the SCXI-1503 What You Need to Get Started ...1-1 National Instruments Documentation ...1-2 Installing Application Software, NI-DAQ, and the E/M Series DAQ Device ...1-4 Installing the SCXI-1503 Module into the SCXI Chassis...1-4 Installing the Terminal Block...1-4 Configuring the SCXI System Software ...1-4...
Page 6
Contents Chapter 4 Theory of Operation Rear Signal Connector, SCXIbus Connector, and SCXIbus Interface... 4-3 Digital Control Circuitry ... 4-3 Analog Circuitry... 4-3 Analog Input Channels... 4-3 Operation of the Current Sources ... 4-4 Theory of Multiplexed Operation... 4-4 Measuring Temperature with Resistive Transducers ... 4-5 RTDs ...
❑ ❑ ❑ National Instruments Documentation The SCXI-1503 User Manual is one piece of the documentation set for data acquisition (DAQ) systems. You could have any of several types of manuals depending on the hardware and software in the system. Use the manuals you have as follows: •...
Page 11
DAQ device, and application hints. Software documentation—You may have both application software and NI-DAQ software documentation. National Instruments (NI) application software includes LabVIEW, LabWindows/CVI, and Measurement Studio. After you set up the hardware system, use either your application software documentation or the NI-DAQ documentation to help you write your application.
Chapter 1 About the SCXI-1503 Installing Application Software, NI-DAQ, and the E/M Series DAQ Device Refer to the DAQ Getting Started Guide packaged with the NI-DAQ software to install your application software, NI-DAQ driver software, and the DAQ device to which you will connect the SCXI-1503. NI-DAQ 8.1 or later is required to configure and program the SCXI-1503 module.
Chapter 2 Connecting Signals Exceeding the differential or common-mode input channel ranges results in a Note distorted signal measurement, and can also increase the settling time requirement of the connected E/M Series DAQ device. Ground-Referencing the Signals Do not ground signals that are already ground-referenced; doing so results in a ground loop, which can adversely affect the measurement accuracy.
Chapter 2 Connecting Signals 2-Wire Configuration The basic 2-wire configuration is shown in Figure 2-2. In this configuration an error voltage (V excitation current (I the error voltage is: This is the most commonly used configuration for connecting thermistors to a signal conditioning system because the large sensitivity of thermistors usually results in the introduction of a negligible error by the lead resistances.
Chapter 2 Connecting Signals Lead-Resistance Compensation Using a 3-Wire Resistive Sensor and Two Matched Current Sources You can compensate for the errors introduced by lead-resistance voltage drops by using a 3-wire resistive sensor and two matched current sources connected as shown in Figure 2-4. SCXI-1503 User Manual External Sensor SCXI-1306...
Chapter 2 Connecting Signals Front Connector Diagram Column NC—no connection RSVD—reserved SCXI-1503 User Manual Table 2-1. Front Signal Pin Assignments Pin Number Column A RSVD RSVD RSVD RSVD RSVD RSVD CJ SENSOR CJ SENSOR CGND +5 V Column B Column C AI0–...
Page 25
Chapter 2 Connecting Signals Table 2-4. SCXI-1503 50-Pin Rear Connector Signals (Continued) SCXI Signal Name SER DAT OU DAQ D*/A SLOT 0 SEL* SCAN CLK AI HOLD COMP, SER CLK 43, 46 RSVD Note: All other pins are not connected. SCXI-1503 User Manual NI-DAQmx Device Signal...
Chapter 3 Configuring and Testing Input Coupling The front end of the SCXI-1503 includes a software configurable switch that allows you to programmatically connect the input channels of the SCXI-1503 to either the front connector or internal ground. When using autozero, the coupling mode is set automatically.
Chapter 3 Configuring and Testing If you want to add channels of various measurement types to the same task, click Note the Add Channels button to select the measurement type for the additional channels. 10. If you are creating a task and want to set timing or triggering controls, 11.
Chapter 4 Theory of Operation Rear Signal Connector SCXIbus Connector 32-to-1 Mux Gain 0 Gain 31 Front Signal Connector Figure 4-1. Block Diagram of SCXI-1503 SCXI-1503 User Manual ni.com...
Chapter 4 Theory of Operation The CJ SENSOR input channel is used to read the sensor temperature from the terminal block. The temperature sensor is for cold-junction compensation of thermocouple measurements. The CJ SENSOR channel also passes through a 5 Hz lowpass filter to reject unwanted noise on the SCXI-1503.
Chapter 4 Theory of Operation changes in resistance, you must use special configurations that minimize measured errors caused by lead-wire resistance. RTD Measurement Errors Because the RTD is a resistive device, you must pass a current through the device and monitor the resulting voltage. However, any resistance in the lead wires that connect the measurement system to the RTD adds error to the readings.
Chapter 4 Theory of Operation Although the resistance-temperature curve is relatively linear, accurately converting measured resistance to temperature requires curve fitting. The following Callendar-Van Dusen equation is commonly used to approximate the RTD curve: where Table 4-1 lists the RTD types and their corresponding coefficients. IEC-751 DIN 43760 BS 1904...
Chapter 4 Theory of Operation Thermistors A thermistor is a piece of semiconductor made from metal oxides, pressed into a small bead, disk, wafer, or other shape, sintered at high temperatures, and finally coated with epoxy or glass. The resulting device exhibits an electrical resistance that varies with temperature.
Chapter 4 Theory of Operation The maximum resistance of the thermistor is determined from the current excitation value and the maximum voltage range of the input device. When using the SCXI-1503, the maximum measurable resistance is 100 k . The level of the voltage output signal depends directly on the thermistor resistance and magnitude of the current excitation.
Chapter 5 Using the SCXI-1503 Create Task in DAQ Assistant or MAX Further Configure Channels? Configure Channels Start Measurement Read Measurement SCXI-1503 User Manual Create Task Using DAQ Assistant? Create Another Channel? Clear Task Figure 5-1. Typical Program Flowchart for Voltage Measurement Channels Create a Task Programmatically Create Channel...
Chapter 5 Using the SCXI-1503 time. For continuous acquisition, you must use a while loop around the acquisition components even if you configured the task for continuous acquisition using MAX or the DAQ Assistant. For continuous and buffered acquisitions, you can set the acquisition rate and the number of samples to read in the DAQ Assistant or programmatically in your application.
Chapter 5 Using the SCXI-1503 Table 5-2. NI-DAQmx RTD Measurement Properties (Continued) Property Analog Input»Temperature» RTD»Custom»A, B, C Analog Input»General Properties»Signal Conditioning»Resistance Configuration Table 5-3. NI-DAQmx Thermistor Measurement Properties Property Analog Input»Temperature» Thermistor»R1 Analog Input»Temperature» Thermistor»Custom»A, B, C SCXI-1503 User Manual Short Name AI.RTD.A Specifies the A, B, or...
Chapter 5 Using the SCXI-1503 charts, graphs, slide controls, and gauge indicators. NI ADEs have tools that allow you to easily save the data to files such as spread sheets for easy viewing, ASCII files for universality, or binary files for smaller file sizes. Completing the Application After you have completed the measurement, analysis, and presentation of the data, it is important to stop and clear the task.
Chapter 5 Using the SCXI-1503 Table 5-5. Programming a Task in LabVIEW (Continued) Flowchart Step Stop Measurement Clear Task Using a NI-DAQmx Channel Property Node in LabVIEW You can use property nodes in LabVIEW to manually configure the channels. To create a LabVIEW property node, complete the following steps: Note If you do not use Active Channels, the properties are set on all of the channels in...
Page 55
Chapter 5 Using the SCXI-1503 Refer to the NI LabWindows/CVI Help for more information on creating NI-DAQmx Note tasks in LabWindows/CVI and NI-DAQmx property information. Measurement Studio (Visual Basic 6, .NET, and C#) When creating an voltage measurement task in Visual Basic 6, .NET and C#, follow the general programming flow in Figure 5-1.
Chapter 5 Using the SCXI-1503 The functions that are required for externally calibrating the SCXI-1503 are available in NI-DAQmx 8.1 or later. Refer to the NI-DAQmx Help for details about these functions. Most external calibration documents for SCXI modules are available to download from Procedures.
Appendix A Specifications Gain error (relative to calibration reference) RTD Measurement Accuracy Measured Temperature C Max C –100 to 0 0.60 0 to 25 0.62 25 to 100 0.69 100 to 500 1.11 500 to 1200 2.06 Notes: The accuracies in this table reflect using the module in4-wire mode. They do not include errors from the RTD including lead-wire errors when using 2- or 3-wire connection.
Page 61
Appendix A Specifications Gain temperature coefficient (gain 1 or 100) ...±15 ppm/ C max Excitation Channels ...16 single-ended outputs Current output...100 A Accuracy ...±0.05% Temperature drift ...±5 ppm/ C Output voltage compliance ...10 V Maximum resistive load ...100 k Overvoltage protection ...±40 VDC Measurement Category...CAT I Power Requirements From SCXI Backplane V+ ...18.5 to 25 VDC, 170 mA...
Waste Electrical and Electronic Equipment (WEEE) EU Customers At the end of their life cycle, all products must be sent to a WEEE recycling center. For more information about WEEE recycling centers and National Instruments WEEE initiatives, visit SCXI-1503 User Manual...
Page 65
Appendix B Removing the SCXI-1503 Remove the SCXI-1503 by pulling steadily on both thumbscrews until the module slides completely out. 1 Cable 2 SCXI Module Thumbscrews SCXI-1503 User Manual Rotate the thumbscrews that secure the SCXI-1503 to the chassis counterclockwise until they are loose, but do not completely remove the thumbscrews.
Page 67
Appendix C Common Questions Can I connect N current-output channels in parallel to create a precision current source that provides N Yes, you can connect the current output in parallel. When connecting the output in parallel, connect the appropriate IEX+ terminals together and the corresponding IEX–...
Page 70
Glossary one binary digit, either 0 or 1 European emissions control standard C GND chassis ground signal channel pin or wire lead to which you apply, or from which you read, an analog or digital signal. Analog signals can be single-ended or differential. For digital signals, channels (also known as lines) are grouped to form ports.
Page 72
(signal) NI-DAQ the driver software needed in order to use National Instruments E/M Series DAQ devices and SCXI components NI-DAQmx The latest NI-DAQ driver with new VIs, functions, and development tools for controlling measurement devices.
Page 74
Glossary sensor a type of transducer that converts a physical phenomenon into an electrical signal SER CLK serial clock signal used to synchronize digital data transfers over the SER DAT IN and SER DAT OUT lines SER DAT IN serial data input signal SER DAT OUT serial data output signal signal conditioning...
Page 77
Index conventions used in the manual, iv creating a task DAQ Assistant, 5-3 programmatically, 5-3 current output channels, questions about, C-1, C-3 current sources, operating, 4-4 custom cables, 2-1 DAQ Assistant, creating a task, 5-3 DAQ device accessing unused analog input channels, C-2 DAQ devices unavailable digital lines, C-2...
Need help?
Do you have a question about the Module SCXI-1503 and is the answer not in the manual?
Questions and answers