Product Introduction

The NI SCXI-1338 is an 8-channel current input shielded terminal block, specifically designed for the SCXI-1120/1120D/1125/1126 high-precision analog input modules, to convert 4–20 mA/0–20 mA industrial current signals into voltage signals, enabling high-precision current measurement. It features a full metal shielded housing with stress release structure, and the standard part number is 777687-38.

Model Interpretation

SCXI: Instrument Signal Conditioning Expansion Platform (NI Modular Signal Conditioning Series).

13xx: Front-end installation terminal block series for SCXI systems.

SCXI-1338: Compatible with SCXI-1120/1125/1126, 8-channel precision current input terminal block. Technical Specifications

Electrical parameters

Adapter module: SCXI-1120, SCXI-1120D, SCXI-1125, SCXI-1126

Number of channels: 8 channels (single-ended/differential selectable)

Current input range: 0–20 mA, 4–20 mA

Precise shunt resistor: 249 Ω per channel, with an accuracy of ±0.1%, temperature drift of 10 ppm/℃, power of 0.25 W

Channel-to-ground/channel-to-channel voltage: 300 Vrms or ±300 VDC (CAT I)

Maximum input current: ±20 mA

Coupling mode: DC coupling

Cold junction compensation: None

Mechanical and environmental parameters

Installation: SCXI standard front-end installation, 2 wing-shaped screws for fixation

Operating temperature: 0℃–50℃

Storage temperature: -20℃–70℃

Relative humidity: 10%–90% (no condensation)

Shielding: Full metal enclosure, suppressing EMI/RFI

Safety compliance: IEC 61010-1, UL 61010-1; EMC: EN 55011 Class A, EN 61326

Interface and communication configuration

Front: 18 screw terminals (8 pairs of signal terminals + 1 pair of grounding terminals), with stress release clips

Back: Dedicated connectors directly connected to the SCXI module front-end, no additional wiring required

Software compatibility: Compatible with NI-DAQmx driver, supports LabVIEW, C/C++, LabWindows/CVI, etc. development environments

Calibration: Supports system-level calibration, terminal board cannot be user-adjustable

Core functions

8-channel precise current-voltage conversion, compatible with industrial standard 4–20 mA/0–20 mA current signals.

Each channel has an independent 249 Ω precise resistor, ensuring high accuracy and stability.

Full metal shielding structure, effectively suppressing electromagnetic interference, ensuring signal integrity in industrial environments.

Screw terminal connections are reliable, vibration-resistant, with stress release design, suitable for long-term online operation.

Compatible with various SCXI high-precision input modules, flexible for adapting to different testing requirements. Applicable scenarios

Industrial Automation: 4–20 mA sensor (pressure, temperature, flow, level) signal acquisition.

Process Control: Multi-channel current signal monitoring for factory automation production lines.

Laboratory Measurement: High-precision current signal calibration and data acquisition system.

Combined with SCXI-1120/1125/1126, build a high-density and high-stability analog input system.

User Manual and Maintenance Instructions Instruction Manual

Before installation, cut off all power supplies. Align the terminal board with the front interface of the module and insert it smoothly, then tighten the fixing screws.

Connect according to the terminal markings: Connect the 8 signal terminals to the current signal, and reliably connect the grounding terminal to the SCXI chassis ground.

When measuring voltage, remove the shunt resistor of the corresponding channel; when measuring current, ensure that the resistor is installed properly.

Configure the input range, sampling rate and channel mode in the software. After completion, data can be collected.

Maintenance instructions

Place the equipment in a dry and ventilated area, maintaining the rated temperature and humidity, and keeping away from strong electromagnetic sources, dust and corrosive gases.

Regularly check if the connection screws are loose, if the terminals are oxidized, and if the insulation layer of the cables is damaged. Handle them promptly.

Cleaning should be done under power-off conditions. Wipe the surface and terminals with isopropyl alcohol, and allow it to dry completely before re-powering.

When the equipment is idle for a long time, remove the terminal board and put it in an anti-static bag, and store it in a cool and dry environment.