National Instruments 9211A Manuale utente
USER GUIDE AND SPECIFICATIONS
USB-9211/9211A
4-Channel, 24-Bit Thermocouple Input Devices
This user guide describes how to use the National Instruments
USB-9211/9211A devices and lists the specifications.
Introduction
The NI USB-9211/9211A data acquisition device provides a USB interface
for four channels of 24-bit thermocouple inputs with integrated signal
conditioning.
The NI USB-9211 consists of two components: an NI 9211 module and a
USB-9161 carrier, as shown in Figure 1. The NI USB-9211A consists of
two components: an NI 9211 module and a USB-9162 carrier, as shown in
Figure 1.
Figure 1. USB-9211/9211A Components
NI 9211
USB-9161/9162
USB-9211/9211A
USB-9211/9211A User Guide and Specifications 2 ni.com
Dimensions
Figure 2 shows the USB-9211/9211A device dimensions.
Figure 2. USB-9211/9211A Series Devices in Inches (Millimeters)
Safety Guidelines
Operate the USB-9211/9211A only as described in these operating
instructions.
Note Although the NI 9211 module may have more stringent certification standards than
the USB-9211/9211A, when used with the USB-9161/9162 carrier, the combined system
may be limited. Refer to the Specifications section for more details.
Hot Surface This icon denotes that the component may be hot. Touching this component
may result in bodily injury.
Caution Do not disconnect I/O-side wires or connectors unless power has been switched
off or the area is known to be nonhazardous.
Caution Do not remove modules unless power has been switched off or the area is known
to be nonhazardous.
Caution The USB-9211/9211A is not certified for use in hazardous locations.
0.998
(25.34)
Hi-Speed USB Carrier
NI USB-9162
5.521
(140.23)
5.426
(137.82)
4.751
(120.68)
4.656
(118.26)
3.469
(88.12)
©National Instruments Corporation 3 USB-9211/9211A User Guide and Specifications
Safety Guidelines for Hazardous Voltages
If hazardous voltages are connected to the module, take the following
precautions. A hazardous voltage is a voltage greater than 42.4 Vpk or
60 VDC to earth ground.
Caution Ensure that hazardous voltage wiring is performed only by qualified personnel
adhering to local electrical standards.
Caution Do not mix hazardous voltage circuits and human-accessible circuits on the same
module.
Caution Make sure that devices and circuits connected to the module are properly
insulated from human contact.
Caution When module terminals are live with hazardous voltages, make sure that the
terminals are not accessible by using the high voltage screw terminal enclosure. Refer to
the Assembling the High Voltage Screw Terminal Backshell section for more information.
Software
Software support for your hardware depends on the carrier being used.
Refer to Table 1 for a list of software support.
Examples are included with each software API. Refer to the corresponding
software Getting Started Guide for more information.
Table 1. Devices and Corresponding Components
Device Carrier Software Support
USB-9211 NI 9161 NI-DAQmx Base
USB-9211A NI 9162 NI-DAQmx
USB-9211/9211A User Guide and Specifications 4 ni.com
Related Documentation
If your device uses NI-DAQmx Base, refer to ni.com to download the
software.
Installing the USB-9211/9211A Device
Installing the Software
Before installing the device, you must install the software you plan to use
with the device. Refer to the Software section of this manual and the
documentation included with the software for more information.
Installing the NI USB-9211/9211A in the USB-9161/9162 Carrier
The NI 9211 module and the USB-9161/9162 carrier are packaged
separately. Refer to Figure 3, while completing the following assembly
steps:
1. Make sure that no signals are connected to the NI 9211 module and the
USB cable is not connected to the device.
2. Remove the protective cover from the 15-pin DSUB connector.
Guide Location
NI-DAQmx Getting Started Guide Accessible from Start»All Programs»
National Instruments»NI-DAQ after install.
NI-DAQmx for USB Devices Getting Started
Guide
Ships with your device and, after install,
is accessible from Start»All Programs»
National Instruments»NI-DAQ.
NI-DAQmx Base Getting Started Guide Accessible from Start»All Programs»
National Instruments»NI-DAQmx
Bases»Documentation after install.
©National Instruments Corporation 5 USB-9211/9211A User Guide and Specifications
3. Align the I/O module with the carrier, as shown in Figure 3.
Figure 3. Module Installation
4. Squeeze the latches and insert the NI 9211 module into the carrier.
5. Press firmly on the connector side of the NI 9211 module until the
latches lock the module into place, as shown in Figure 4.
Figure 4. Locking Module into Place
6. Connect the USB cable to the assembled USB-9211/9211A.
1 High Voltage Screw Terminal Backshell
1
USB-9211/9211A User Guide and Specifications 6 ni.com
Mounting the USB-9211/9211A to a Panel
Threaded inserts are located in the USB-9211/9211A for mounting it to a
panel. Refer to Figure 5 for dimensions.
Figure 5. Module Dimensions
Connecting the USB-9211/9211A to a Computer
Plug one end of the USB cable into the USB-9211/9211A and the other end
into an available USB port on the computer.
LED Indicator
The LED indicator indicates device status.
Table 2. LED State/Device Status
LED State Device Status
Not lit Device not connected or in suspend.
On, not blinking Device connected, but no module installed.
Single-blink Operating normally.
Double-blink Operating normally.
Quadruple-blink Device error. Refer to ni.com/support.
Threaded Insert
M3 x 0.5
8.5 mm (0.34 in.) Max Depth
72.2 mm
(2.84 in.)
85.7 mm
(3.37 in.)
76.1 mm
(3.00 in.)
©National Instruments Corporation 7 USB-9211/9211A User Guide and Specifications
Wiring the USB-9211/9211A
The USB-9211/9211A has a 10-terminal, detachable high voltage screw
terminal enclosure that provides connections for four thermocouple input
channels. Each channel has a terminal to which you can connect the
positive lead of the thermocouple, TC+, and a terminal to which
you can connect the negative lead of the thermocouple, TC–. The
USB-9211/9211A also has a common terminal, COM, that is internally
connected to the isolated ground reference of the module.
Caution The high voltage screw terminal backshell must be installed when using
hazardous voltages (>42.4 Vpk, 60 VDC).
If you are unsure which of the thermocouple leads is positive and which is
negative, check the thermocouple documentation or the thermocouple wire
spool. If you are using shielded wiring, connect one end of the shield to the
COM terminal.
Figure 6. Connecting a Thermocouple Input Signal to the USB-9211/9211A
Thermocouple
TC–
TC+
Shield
USB-9211/9211A
COM
USB-9211/9211A User Guide and Specifications 8 ni.com
Refer to Table 3 for the terminal assignments for each channel.
Assembling the High Voltage Screw Terminal Backshell
The high voltage screw terminal backshell must be installed when using
hazardous voltages (>42.4 Vpk, 60 VDC). Refer to Figure 7 while
completing the following steps:
1. Connect the leads to the screw terminal and secure with the strain
relief.
2. Finish by snapping the backshell around the connector.
Table 3. Terminal Assignments
Module Terminal Signal
0TC0+
1TC0–
2TC1+
3TC1–
4TC2+
5TC2–
6TC3+
7TC3–
8No connection
9Common (COM)
0
1
2
3
4
5
6
7
8
9
©National Instruments Corporation 9 USB-9211/9211A User Guide and Specifications
Figure 7. High Voltage Screw Terminal Backshell
USB-9211/9211A Circuitry
The USB-9211/9211A channels share a common ground that is isolated
from the chassis and the host computer. Each channel has an impedance
between the TC+and COM terminals and between the TC– and COM
terminals. Each channel is filtered and then sampled by a 24-bit
analog-to-digital converter (ADC). There is a current source between the
TC+ and TC– terminals. If an open thermocouple is connected to the
channel, the current source forces a full-scale voltage across the terminals.
Effects of Source Impedance on Voltage Measurement Accuracy
The resistors shown in Figure 8 produce an input impedance at the
terminals of the USB-9211/9211A.
1 Strain Relief
1
USB-9211/9211A User Guide and Specifications 10 ni.com
Figure 8. Input Circuitry for One Channel
If thermocouples are connected to the USB-9211/9211A, the gain and
offset errors resulting from the source impedance of the thermocouples are
negligible for most applications. Other voltage sources with a higher source
impedance can introduce more significant errors. For more information
about errors resulting from source impedance, refer to the Specifications
section.
Determining Temperature Measurement Accuracy and
Minimizing Errors
Temperature measurement errors depend in part on the thermocouple type,
the temperature being measured, the accuracy of the thermocouple, and the
cold-junction temperature.
Using the Autozero Channel
The USB-9211/9211A has an internal autozero channel for measuring the
offset error. If the ambient temperature of the USB-9211/9211A is less than
15 °C or more than 35 °C, use this channel to read the offset error. The
USB-9211 always has this channel enabled. Use NI-DAQmx to configure
the behavior of the autozero channel for the USB-9211A. Refer to the
NI-DAQmx Help, accessible from Start»All Programs»National
Instruments»NI-DAQ, for more information.
TC+
TC–
COM
USB-9211/9211A
Input
Impedance
Open
Thermocouple
Detection
Current
Filtered
Differential
Amplifier
Isolated
ADC
10 MΩ
10 MΩ
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