NI-9219 Getting Started

Connector Types

The NI-9219 is available in two types: push-in spring terminal and spring terminal. The push-in type spring terminal connector is black and orange. The spring terminal connector is black. NI-9219 refers to both types unless the two types are specified. Differences between the two types of spring terminal connectors are noted by the connector color.

NI-9219 with Spring Terminal (Black Connector) Pinout


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Table 1. Signals by Mode
Mode Pin
1 2 3 4 5 6
Voltage T+ T- — HI LO —
Current T+ T- HI — LO —
4-Wire Resistance T+ T- EX+ HI EX- LO
2-Wire Resistance T+ T- HI — LO —
Thermocouple T+ T- — HI LO —
4-Wire RTD T+ T- EX+ HI EX- LO
3-Wire RTD T+ T- EX+ — EX- LO
Quarter-Bridge T+ T- HI — LO —
Half-Bridge T+ T- EX+ HI EX- —
Full-Bridge T+ T- EX+ HI EX- LO
DI T+ T- — HI LO —
Open Contact T+ T- HI — LO —
Table 2. Signal Descriptions
Signal Description
EX+ Positive sensor excitation connection
EX- Negative sensor excitation connection
HI Positive input signal connection
LO Negative input signal connection
T+ TEDS data connection
T- TEDS COM connection

NI-9219 with Push-in Style Spring Terminal (Black/Orange Connector) Pinout


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Table 3. Signals by Mode
Mode Pin
1 2 3 4 5 6
Voltage T+ T- — HI LO —
Current T+ T- HI — LO —
4-Wire Resistance T+ T- EX+ HI EX- LO
2-Wire Resistance T+ T- HI — LO —
Thermocouple T+ T- — HI LO —
4-Wire RTD T+ T- EX+ HI EX- LO
3-Wire RTD T+ T- EX+ — EX- LO
Quarter-Bridge T+ T- HI — LO —
Half-Bridge T+ T- EX+ HI EX- —
Full-Bridge T+ T- EX+ HI EX- LO
DI T+ T- — HI LO —
Open Contact T+ T- HI — LO —
Table 4. Signal Descriptions
Signal Description
EX+ Positive sensor excitation connection
EX- Negative sensor excitation connection
HI Positive input signal connection
LO Negative input signal connection
T+ TEDS data connection
T- TEDS COM connection

Measurement Types

The NI-9219 provides modes for the following measurement types.

  • Voltage
  • Current
  • 4-Wire Resistance
  • 2-Wire Resistance
  • Thermocouple
  • 4-Wire RTD
  • 3-Wire RTD
  • Quarter-Bridge
  • Half-Bridge
  • Full-Bridge
  • Digital In1 Only supported in CompactRIO systems. [1]
  • Open Contact[1]

Thermocouple Connections


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Changes in the ambient air temperature near the front connector or a thermocouple wire conducting heat directly to terminal junctions can cause thermal gradients. Observe the following guidelines to minimize thermal gradients and improve the system accuracy.

  • Use small-gauge thermocouple wire. Smaller wire transfers less heat to or from the terminal junction.
  • Avoid running thermocouple wires near hot or cold objects.
  • Minimize adjacent heat sources and air flow across the terminals.
  • Keep the ambient temperature as stable as possible.
  • Make sure the NI-9219 terminals are facing forward or upward.
  • Keep the NI-9219 in a stable and consistent orientation.
  • Allow the thermal gradients to settle after a change in system power or in ambient temperature. A change in system power can happen when the system powers on, the system comes out of sleep mode, or you insert/remove modules.

Digital In Connections


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The digital in measurement type is only supported in CompactRIO systems.

Tip Visit ni.com/info and enter the Info Code 9219cdaq for information about implementing the digital in measurement type in CompactDAQ systems.

Open Contact Connections


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The open contact measurement type is only supported in CompactRIO systems.

Tip Visit ni.com/info and enter the Info Code 9219cdaq for information about implementing the open contact measurement type in CompactDAQ systems.

TEDS Connections


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For more information about TEDS, visit ni.com/info and enter the Info Code rdteds.

NI-9219 Connection Guidelines

  • Make sure that devices you connect to the NI-9219 are compatible with the module specifications.
  • Use shielded cables and twisted pair wiring for the best signal quality.
  • NI recommends using the NI-9972 backshell for all connections to the NI-9219.
  • You can connect ground-referenced signal sources to the NI-9219. The following figure illustrates a grounded connection for a voltage source.
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  • You can connect floating signal sources to the NI-9219. Ensure that the voltages on the HI and LO connections are within the channel-to-earth working voltage range. The following figure illustrates a floating connection for a voltage source.
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Connecting to a Spring-Terminal Connector

What to Use

  • NI-9219 spring-terminal connector
  • 0.08 mm2 to 1.0 mm2 (28 AWG to 18 AWG) copper conductor wire with 7 mm (0.28 in.) of insulation stripped from the end
  • Flathead screwdriver with a 2.3 mm x 1.0 mm (0.09 in. x 0.04 in.) blade, included with the NI-9219

What to Do

Complete the following steps to connect wires to the spring-terminal connector.


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  1. Insert the screwdriver into a spring clamp activation slot to open the corresponding connector terminal.
  2. Press a wire into the open connector terminal.
  3. Remove the screwdriver from the activation slot to clamp the wire into place.

High-Vibration Application Connections

If your application is subject to high vibration, NI recommends that you use the NI-9972 backshell kit to protect connections to the NI-9219.

Excitation Protection

The NI-9219 protects the excitation circuit from overcurrent and overvoltage fault conditions. The NI-9219 automatically disables the circuit in the event of a fault condition. Whenever possible, channels automatically recover after the fault is removed.

Note Refer to the device datasheet on ni.com/manuals for more information about excitation protection.

Measurement Type Pinout

The following sections include pinouts for the NI-9219 measurement types.

NI-9219 Block Diagram


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  • The NI-9219 is channel-to-channel isolated.
  • Four 24-bit analog-to-digital converters (ADCs) simultaneously sample all four analog input channels.
  • The NI-9219 enables an excitation circuit for all input modes that require excitation.
  • The NI-9219 reconfigures the signal conditioning for each measurement type.

Voltage Block Diagram


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  • The ADC measures voltage across the HI and LO terminals.
  • The NI-9219 has ±60 V, ±15 V, ±4 V, ±1 V, and ±125 mV voltage ranges.

Current Block Diagram


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The NI-9219 computes current from the voltage that the ADC measures across an internal shunt resistor.

Thermocouple Block Diagram


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  • The NI-9219 uses the ±125 mV range of the ADC to return a voltage reading.
  • Each channel has a built-in thermistor for cold-junction compensation (CJC) calculations.

4-Wire Resistance and 4-Wire RTD Block Diagram


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  • The NI-9219 sources a current, which varies based on the resistance of the load, between the EX+ and EX- terminals. The NI-9219 computes measured resistance from the resulting voltage reading.
  • Lead wire resistance does not affect these measurement types because a negligible amount of current flows across the HI and LO terminals due to the high input impedance of the ADC.

3-Wire RTD Block Diagram


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  • The NI-9219 sources a current, which varies based on the resistance of the load, between the EX+ and EX- terminals.
  • The NI-9219 compensates for lead wire resistance in hardware if all the lead wires have the same resistance.
  • The NI-9219 applies a gain of 2x to the voltage across the negative lead wire and the ADC uses this voltage as the negative reference to cancel the resistance error across the positive lead wire.

2-Wire Resistance and Quarter-Bridge Block Diagram


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  • The NI-9219 sources a current, which varies based on the resistance of the load, between the HI and LO terminals.
  • The NI-9219 computes measured resistance from the resulting voltage reading.
  • 2-Wire Resistance and Quarter-Bridge measurement types do not compensate for lead wire resistance.

Full-Bridge Block Diagram


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  • The ADC reads the HI and LO inputs differentially.
  • The internal voltage excitation sets the input range of the ADC and returns voltage readings that are proportional to the excitation level. The internal excitation voltage varies based on the resistance of the sensor.

Half-Bridge Block Diagram


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  • The HI input is referenced to EX-.
  • The internal voltage excitation sets the input range of the ADC and returns voltage readings that are proportional to the excitation level. The internal excitation voltage varies based on the resistance of the sensor.

Digital In Block Diagram


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  • The NI-9219 has a 60 V unipolar threshold that you can set in software.
  • The digital in measurement type is only supported in CompactRIO systems.

Open Contact Block Diagram


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  • The NI-9219 sources a current between the HI and LO terminals and determines if the two terminals are open or closed based on the measured current through the terminals.
  • When the circuit is open, make sure no more than ±60 V is sourced across the switch.
  • The open contact measurement type is only supported in CompactRIO systems.

Conformal Coating

The NI-9219 is available with conformal coating for additional protection in corrosive and condensing environments, including environments with molds and dust.

In addition to the environmental specifications listed in the NI-9219 Safety, Environmental, and Regulatory Information, the NI-9219 with conformal coating meets the following specification for the device temperature range. To meet this specification, you must follow the appropriate setup requirements for condensing environments. Refer to Conformal Coating and NI RIO Products for more information about conformal coating and the setup requirements for condensing environments.

Operating humidity (IEC 60068-2-30 Test Db) 80 to 100% RH, condensing

1 Only supported in CompactRIO systems.