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USER GUIDE
SCC-AI Series Isolated Analog
Input Modules
The SCC-AI Series isolated analog input modules (SCC-AIXX) can extract
a relatively low-amplitude input signal from a high-common-mode voltage
so the E Series DAQ device can measure the input signal. They also can
amplify and filter the input signal, resulting in higher measurement
resolution and accuracy.
SCC-AIXX modules are available in a range of gains from 0.2 to 200. They
contain lowpass filters of either 10 kHz or 4 Hz bandwidt
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Conventions The following conventions are used in this guide: <> Angle brackets that contain numbers separated by an ellipsis represent a range of values associated with a bit or signal name—for example, ai<0..7>. This icon denotes a note, which alerts you to important information. This icon denotes a caution, which advises you of precautions to take to avoid injury, data loss, or a system crash. When this symbol is marked on the product, refer to the Read Me First: Safety and Radio-Frequenc
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❑ One or more SCC-SGXX ❑ SCC-SG Series Strain-Gauge Modules User Guide ❑ SC-2345 User Manual ❑ Read Me First: Safety and Radio-Frequency Interference ❑ SC-2345 Quick Reference Label ❑ 68-pin Basic or E Series DAQ device, documentation, and 68-pin cable ❑ 1/8 in. flathead screwdriver ❑ Numbers 1 and 2 Phillips screwdrivers ❑ Wire insulation strippers ❑ NI-DAQ (current version) for Windows 2000/NT/XP/Me Note Software scaling of measurements is not supported on the Macintosh operating system. Ref
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Installing the Module Caution Refer to the Read Me First: Safety and Radio-Frequency Interference document before removing equipment covers or connecting/disconnecting any signal wires A blue label stripe identifies the SCC-AIXX as an analog input module. The label also displays the icon shown in Figure 1-1. Figure 1-1. SCC-AIXX Icon You can plug the SCC-AIXX into any analog input socket on the SC-2345. The socket you choose determines which E Series DAQ device channels receive the SCC-AI
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4 3 2 1 Connecting the Input Signals The SCC-AIXX has a fixed screw-terminal receptacle and a removable screw-terminal block, as shown in Figure 1-2. 1 2 1 SCC Screw-Terminal Receptacle 2 Removable Screw-Terminal Block Figure 1-2. SCC-AIXX Two-Part Screw-Terminal System After you install the SCC-AIXX, connect the input signals to the removable screw-terminal block of the module. 1. Remove power from the signal lines. 2. Strip 7 mm of insulation from the ends of the signal wires. 3. Insert t
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SCC-AIXX E Series DAQ Device Signal Source 4 + + Lowpass – ACH(X ) Filter 3 – AISENSE AIGND 2 + + Lowpass ACH(X+8) – Filter 1 – Figure 1-3. SCC-AIXX Signal Connections The inputs are designed in a floating (nonreferenced) single-ended configuration. If the measured signals are floating, connect the negative input pins, 1 and 3, to AISENSE on the SC-2345 terminal block through a10kΩ to 100 kΩ resistor. Figure 1-4 shows a floating signal connection on one channel of the SCC-AIXX. E Series
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If a high common-mode voltage is present, connect the negative input pins, 1 and 3, to the signal reference. Figure 1-5 shows a ground-referenced signal connection on one channel of the SCC-AIXX. SCC-AIXX E Series DAQ Device 4 + + Signal Lowpass Source – ACH(X ) Filter 3 – + High AISENSE CMV – AIGND 2 + Lowpass ACH(X+8) Filter 1 – Figure 1-5. Ground-Referenced Signal Connection for the SCC-AIXX with High Common-Mode Voltage (One Channel) Configuring the SCC System Measurement & Automation E
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4. In the SCC Connector Block Configuration window, configure the SCC system as follows: a. Specify the SCC Carrier Type. The location of the SCC sockets change depending on the SCC carrier type. b. Select the DAQ Device that is connected to the SC-2345. c. Type the SCC Connector Block ID. The default value is SCC1. d. In the J21 drop-down list next to Power, select the correct SC-2345 power configuration. Refer to the SC-2345 User Manual for information on power configurations. e. For each
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10. If you make a selection mistake, select the socket and click Remove. 11. Repeat steps 8 and 9 for each newly installed SCC. 12. Click OK after completing all SCC entries. 13. Click OK to complete the configuration process and close MAX. Note Configuring the SCC system using MAX automatically sets the E Series DAQ device analog input mode to nonreferenced single-ended (NRSE). Virtual Channels, Physical Channels, and Tasks After you have installed and configured your SCC hardware, you can use
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Table 1-2 shows suggested values for some of the parameters. Use default values for parameters not shown. Table 1-2. SCC-AIXX Suggested Values Module Input Range SCC-AI01 ±42 V SCC-AI02 ±20 V SCC-AI03 ±10 V SCC-AI04 ±5 V SCC-AI05 ±1 V SCC-AI06 ±100 mV SCC-AI07 ±50 mV SCC-AI13 ±10 V SCC-AI14 ±5 V 9. Click Test to test the channel. You should be able to view your measurement in the window that appears. You have finished configuring the NI-DAQmx task or global channel. Creating a Virtual Channel
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Scaling Voltage Measurements If you configured the SCC-AIXX using MAX and you are using NI-DAQ, the voltage reading you get from the E Series DAQ device accounts for the voltage scaling effect of the SCC-AIXX. Otherwise, since the voltage measurement from the E Series DAQ device is scaled by the gain given in Table 1-1, you must divide the voltage reading returned by the E Series DAQ device by this gain to get the correct input voltage. Specifications These ratings are typical at 25 °C unle
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Filter Characteristics Number of poles .....................................3 Rolloff.....................................................60 dB/decade Cutoff frequency (–3 dB) AI0X ................................................10 kHz AI1X ................................................4 Hz Power Requirement Analog power .........................................519 mW max +15 V ...............................................34.6 mA max –15 V ...............................................34.6
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Environmental Operating temperature............................ 0 to 50 °C Storage temperature ............................... –20 to 70 °C Humidity ................................................ 10 to 90% RH, noncondensing Maximum altitude.................................. 2,000 meters Pollution Degree (indoor use only)........ 2 Safety The SCC-AIXX meets the requirements of the following standards for safety and electrical equipment for measurement, control, and laboratory use: IEC 61010
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Calibrating Gain and Offset Errors The SCC-AIXX is calibrated at the factory before shipment. If you want to adjust the gain of the SCC-AIXX in your system using your E Series DAQ device, you need a voltage source that is several times more accurate than the SCC itself and capable of providing the DC voltage shown in Table 1-3. Table 1-3. SCC-AIXX Input Voltage Requirements Module Input Range SCC-AI01 40 V SCC-AI02 16 V SCC-AI03 8 V SCC-AI04 4 V SCC-AI05 800 mV SCC-AI06 80 mV SCC-AI07 40 mV
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9. Adjust the trimpot labeled Gain located on the top of the SCC-AIXX. If the value you obtained in step 8 is less than the input voltage, turn the trimpot clockwise to increase the gain. If it is greater than the input voltage, turn the trimpot counterclockwise to decrease the gain. 10. Repeat steps 4 through 9 until the difference you get in step 8 equals the Input Voltage Required value shown in Table 1-3; in this example the value is 8 V using an SCC-AI03. For example, assume that you h
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SCC-AIXX Module Pin Assignments Figure 1-6 shows the I/O connector pins on the bottom of the module. 4 1 2 3 5 1Pin 1 2Pin 2 3PWB Key 4 Pin 19 5Pin 20 Figure 1-6. SCC Module Bottom View Table 1-4 lists the signal corresponding to each I/O connector pin on the bottom of the SCC-AIXX. ACH(X) and ACH(X+8) are the analog input channels of the E Series DAQ device. AIGND is the analog input ground signal and is the reference for ACH(X) and ACH(X+8). AGND is the reference for the ±15 V supplies
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Table 1-4. SCC-AIXX Module Pin Assignments (Continued) Pin Number Signal 9 +6 V 10 GND 11 AGND 12 REF5V 13 +15 V 14 –15 V 15 — 16 — 17 — 18 — 19 — 20 — © National Instruments Corporation 17 SCC-AI Series Isolated Analog Input Modules
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