High-Precision Data Acquisition
NI PCI-4351, NI PXI-4351
◾◾ Temperature and voltage loggers ◾◾ Accuracy – 0.42 °C for J-type thermocouples, 0.03 °C for thermistors, 0.12 °C for RTDs ◾◾ 16 voltage or 12 thermocouple inputs; up to 60 readings/s ◾◾ 8 digital I/O lines (TTL) ◾◾ Autozero and cold-junction compensation Operating Systems ◾◾ Windows XP/2000/NT ◾◾ LabVIEW Real-Time Recommended Software ◾◾ LabVIEW ◾◾ LabWindows™/CVI ◾◾ Measurement Studio Driver Software (included) ◾◾ NI-435x instrument driver ◾◾ Traditional NI-DAQ (Legacy)
Family NI 4351
Bus PCI, PXI
Voltage/ (Thermocouple) Channels 16/(14)
RTD Accuracy (°C) 0.12
Thermistor Accuracy (°C) 0.03
reject 50, 60, and 400 Hz noise, based on the reading rate. The input circuitry
Resistance Measurement Excellent
delivers ±42 V overvoltage protection and per-channel lowpass, antialiasing filters. An NI 4351 device features software-selectable ground referencing on a channel-by-channel basis, so you can measure both floating and groundreferenced signals together; it also features per-channel open-thermocouple detection. When open-thermocouple detection is enabled, the input channel is connected to +2.5 VDC through a 10 MΩ resistor. When a thermocouple breaks or is disconnected, the reading rapidly increases to 100 mV or more, indicating an open-circuit condition.
Table 1. High-Precision DAQ Selection Guide
Overview
The NI PCI-4351 and PXI-4351 are precision computer-based digitizers designed specifically for high-accuracy temperature measurements (thermocouples, RTDs, thermistors), resistance measurements, chromatography measurements, and low-frequency analog signal measurements within ±15 V. Available for PCI and PXI/CompactPCI, these devices feature ±0.42 °C, J-type thermocouple accuracy; ±0.12 °C RTD accuracy; ±0.03 °C thermistor accuracy; 5½-digit voltage measurements; power line noise rejection filters; and precision current source for RTD and thermistor excitation. NI 4351 devices combine the functionality of stand-alone temperature and voltage meters and chromatographs with the flexibility and benefits of your computer, so you can build highly capable computer-based data-logging systems. As with all computer-based digitizers, NI 4351 devices can easily integrate into your Internet-based applications.
Precision Current Excitation
These devices feature a 25 μA precision current source for excitation of RTDs, thermistors, or other resistive devices. The source excites the total system resistance of up to 600 kΩ. An NI 4351 also features an additional 1 mA precision current source for RTDs or other resistive devices for total system resistance of up to 15 kΩ.
Digital I/O and Alarm Outputs
An NI 4351 has eight 5 V/TTL digital lines. You can individually configure each line as an input or an output. You can use the lines as general-purpose digital I/O or as control lines for alarms. Each line sinks or sources 8 mA. With the TBX-68T or CB-68T, you can increase the sinking and sourcing capability of these digital lines to 64 and 15 mA, respectively. With digital signal conditioning accessories, such as the ER-8, SSR Series, and the SC-206x, you can use an NI 4351 to control relays and drive optically isolated digital I/O.
Hardware
Precision Analog Input
NI 4351 devices have 16 differential analog inputs. Each device has a 24-bit analog-to-digital converter (ADC) and six possible reading rates – 10, 50, and 60 readings/s in single-channel acquisition mode and 2.8, 8.8, and 9.7 total readings/s in multiple-channel acquisition mode. For channel speed, divide the total readings/s by the number of channels acquired. Digital filters automatically
High-Precision Data Acquisition
I/O Connector
NI 4351 devices have a 68-pin shielded latched male connector. ACH± are the 8/16 differential analog input channels. AGND is the analog ground. IEX± are for the current excitation sources (25 μA and 1 mA). DIO are the TTL lines and are referenced to DGND.
Recommended Accessories
You can choose from several accessories, shown in Table 2, to accurately measure temperature, voltage, or resistance.
Measurement Type Thermocouple only Voltage, resistance, chromatography only Temperature, voltage, resistance, chromatography NI 435x Platforms PCI, PXI PCI, PXI PCI, PXI Accessory TC-2190 and SH6868 cable TBX-68 and SH6868 cable TBX-68T and SH6868 cable; CB-68T with CA-1000 and SH6868 cable
Software
Instrument Driver
Use the NI-435x instrument driver to integrate a device into your test software. The instrument driver works with: ◾◾ NI LabVIEW ◾◾ NI Measurement Studio ◾◾ Visual C/C++ ◾◾ Visual Basic With a computer-based NI 4351 device, you can create distributed measurement systems with ease, taking full advantage of the Web.
Table 2. NI 435x Accessory Selection Guide
Ordering Information
NI PCI-4351 .................................................................................... 777789-01 NI PXI-4351 .................................................................................... 777790-01
Includes instrument driver. For more information on extended warranty and value-added services, visit ni.com/services.
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For complete product specifications, pricing, and accessory information, call 800 813 3693 (U.S.) or go to ni.com/daq.
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2
High-Precision Data Acquisition
TC-2190 – Shielded, rack-mount adapter with 14 thermocouple miniconnectors, spring terminals for four digital I/O lines, isothermal construction, a cold-junction sensor on channel 0, and autozeroing circuitry on channel 1. Use with the SH6868 shielded cable. TC-2190 .................................................777510-01 TBX-68T, CB-68T – 68-pin, DIN-rail mountable terminal block with screw terminals for 14 unconditioned temperature, voltage, or resistance signals as well as for excitation. The TBX-68T also has eight digital I/O lines, isothermal design for cold-junction compensation, and autozeroing circuitry on channel 1. The CB-68T is similar to the TBX-68T but is designed to mount inside the CA-1000 custom connectivity enclosure. Both the TBX-68T and CB-68T provide circuitry to increase your sinking and sourcing capabilities to 64 and 15 mA, respectively. They also have two 26-pin connectors to which you can connect digital signal conditioning accessories such as the SSR-8, ER-8, and the SC-206x. TBX-68T .................................................777232-01 CB-68T ...................................................777926-01 TBX-68 – General-purpose terminal block to which you can connect up to 16 unconditioned analog signals as well as excitation and digital signals. Use the TBX-68 with the SH6868 shielded cable. TBX-68 ...................................................777141-01 SH6868 – 68-pin shielded cable terminated with two 68-pin 0.050 series D-type connectors. The cable is used to connect an NI 4351 device to 68-pin accessories such as the TC-2190, TBX-68T, TBX-68, and CB-68T. 1 m ......................................................182419-01 2 m ......................................................182419-02
TC-2190
TBX-68T
CB-68T and CA-1000
TBX-68
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High-Precision Data Acquisition Specifications
» For complete specifications, see the NI 435x User Manual
at ni.com/manuals.
Thermistor Accuracy
Temperature ......................................... Error ...................................................... Temperature coefficient .......................
Temperature Coefficient (°C/°C) 0.02 Accessory Error (°C) 0.25
0 to 50 °C 0.03 °C 0.001 °C/°C
Thermocouple Accuracy
Error (°C) TC Type J °C -100 0 760 K -100 0 1,000 1,372 N -100 0 400 1,300 E -100 0 500 1,000 T -150 0 400 R 250 1,000 1,767 S 250 1,000 1,767 B 600 1,000 1,820 10 Hz 0.53 0.42 0.42 0.60 0.45 0.60 0.74 0.68 0.54 0.42 0.57 0.55 0.41 0.35 0.46 0.81 0.46 0.33 0.82 0.72 0.91 0.91 0.77 0.96 1.08 0.76 0.74 50 Hz 0.61 0.49 0.47 0.72 0.54 0.69 0.84 0.84 0.67 0.51 0.66 0.62 0.46 0.40 0.50 0.96 0.55 0.39 1.16 0.99 1.19 1.28 1.05 1.27 1.64 1.14 1.05 60 Hz 0.74 0.59 0.55 0.89 0.67 0.81 0.99 1.08 0.86 0.65 0.80 0.74 0.55 0.46 0.57 1.17 0.68 0.47 1.65 1.37 1.60 1.83 1.47 1.72 2.47 1.69 1.50 0.11 0.00 0.07 0.13 0.06 0.12 0.03 0.36 0.02 0.28 0.03 0.26 0.03 0.27
Resistance Accuracy and DC Voltage Accuracy
For detailed resistance accuracy and DC voltage accuracy specifications, see the NI 435x User Manual at ni.com/manuals.
Analog Input
Input characteristics Number of channels ......................... Digits................................................. Type of ADC ...................................... ADC resolution.................................. Calibration cycle ...............................
Mode Single channel 10 50 60 Multiple-channel2 scanning 2.8 (1.41) 8.8 (2.11) 9.7 (2.1 )
1
16 differential or 14 temperature 5½ Delta-sigma 24 bits, no missing codes 1 year
Power Line Noise Rejection (Hz) 50, 60, 400 50, 400 60 50, 60, 400 50, 400 60
Reading Rate (Readings/s)
Resistance ranges >50 k 2 Total number of readings per second (for single-channel speed, divide by the number of channels acquired)
1
Reading Rates
Input coupling........................................ Range >2.5 V..................................... Range ≤2.5 V .................................... Overvoltage protection (ACH, IEX± ) ............. ±42 V powered on, ±17 V powered off Interrupts, programmed I/O 30 minutes Data transfers .......................................
60 Hz I
1 EX1
DC Each input should remain within ±15 V of ground Each input should remain within ±2.5 V of ground
Maximum working voltage (signal + common mode)
RTD Accuracy
Error (°C) (100 Ω RTD) 10 Hz °C -200 0 100 300 600
1
50 Hz I
2 EX0
I
1 EX1
I
1 EX1
I
2 EX0
I
2 EX0
Temperature Coefficient (°C/°C) 0.02 – – – –
Warm-up time .......................................
0.05 0.12 0.16 0.23 0.36
1.00 1.14 1.22 1.38 1.66
0.06 0.13 0.17 0.24 0.37
1.33 1.49 1.58 1.76 2.08
0.07 0.14 0.18 0.26 0.39
1.81 2.00 2.10 2.32 2.69
Amplifier Characteristics
Input impedance Normal powered on .......................... Powered off ...................................... Overload............................................ >1 GΩ in parallel with 0.39 µF 10 kΩ 10 kΩ
With 100 Ω RTD, 25 µA current source. 2With 100 Ω RTD, 1 mA current source (NI 4351 only) .
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High-Precision Data Acquisition
Open-thermocouple detection .............. Ground-referencing ............................... Input bias current .................................. CMR (DC, 50 Hz, 60 Hz, 400 Hz) Range ≥2.5 V .................................... Range 100 dB 10 MΩ between CH+ and +2.5 V (software selectable) 10 MΩ between CH- and ground (software selectable)