OE Max Controls NX70 series PLC

NX70 Series Programmable Logic Controller: High Performance Small PLC System

In the field of industrial automation, small programmable logic controllers (PLCs) need to provide high processing speed, flexible I/O expansion, rich communication interfaces, and reliable memory backup in a compact size. The OEMax NX70 series controller is designed to meet these requirements, using high-speed ASIC technology with a basic instruction processing time of only 0.2 μ s/step, supporting up to 384 I/O points, and providing multiple dedicated modules (analog, temperature, high-speed counting, motion control, etc.) as well as strong communication protocols. This article will provide a comprehensive and in-depth technical analysis of the series of controllers from the aspects of system configuration, hardware specifications, addressing methods, installation and wiring, programming instruction set, communication protocol, and selection guide.

System characteristics and configuration

The NX70 series PLC adopts a modular chassis structure, which provides multiple models such as 2, 3, 5, 6, 8, 10, and 12 slots. The power module, processor module, and I/O module are installed in left to right order. The system is not expandable (i.e. cannot increase the number of slots by adding a motherboard), but I/O capacity can be flexibly configured by selecting a motherboard with different numbers of slots.

1.1 Processor module

NX70-CP70p1: Program capacity of 9.6k words, 1 RS232/RS485 communication port, basic instructions of 0.2 μ s/step, embedded flash ROM for program backup.

NX70-CP70p2: Program capacity of 20k words, 2 independent communication ports (COM1 and COM2), supports real-time clock (RTC) and PID functions, embedded flash ROM. The COM2 port supports user-defined communication protocols (binary communication) and can be connected to barcode readers, frequency converters, servo drives, etc.

1.2 Power module

NX70-POWER1: AC 110~220V input, output 5V/4.0A and 24V/0.3A.

NX70-POWER2: AC 110~220V input, output 5V/4.5A (no 24V output).

NX70-PWRDC: DC 24V input, output 5V/4.5A.

The power module provides 5V power to all modules through the internal bus of the motherboard. The 24V control power supply (used for input modules and output loads) can be provided by an external commercial power supply or the 24V terminal of POWER1, but parallel use is prohibited.

1.3 I/O module

NX70 supports a wide range of digital and analog modules:

Digital input: 16/32 point DC input (12-24V or 24V), 16 point AC input (110V or 220V).

Digital output: 8/16 point relay output (3A or 1A), 16/32 point transistor output (NPN or PNP), 16 point SSR output.

Combination module: 8 inputs/8 outputs (DC input+relay output), 16 inputs/16 outputs (DC input+transistor output).

Simulation module: 4-channel A/D (voltage/current, 16 bits), 2/4-channel D/A (voltage/current, 14 bits), 4-channel RTD (thermistor), Pt/Ni/Cu）、 4-channel TC (thermocouple, B/R/S/N/K/E/J/T）。

Motion control module: 1/2/4 channel high-speed counter (up to 200 kcps, 32-bit), 4-channel pulse output (up to 100 kHz, with directional control), 4-channel PWM output (30 kHz).

Communication modules: SCU (Serial Communication Unit, RS232/RS485), DeviceNet slave, MW Link network module.

1.4 Programming Tools

Use WinGPC (Windows version) programming software (current version 3. xx) to connect the processor module via RS232/RS485 cable (NX_CBLCPU2/5). Supports programming languages such as ladder diagrams and instruction lists, and allows online editing, forced I/O, timing diagram monitoring, and other functions.

Hardware specifications and installation points

2.1 Environmental and Mechanical Specifications

Working temperature: 0~55 ° C, storage temperature: -25~70 ° C

Humidity: 30~85% RH (without condensation)

Voltage endurance: AC terminal to ground 1500V AC/1 minute, DC terminal to ground 500V AC/1 minute

Insulation resistance: ≥ 100 M Ω (500V DC)

Anti vibration: 10~55 Hz, amplitude 0.75 mm, X/Y/Z for 10 minutes each

Impact resistance: 98 m/s ², 4 times each for X/Y/Z

Installation method: The base plate is fixed inside the control cabinet with M5 screws, and the module is fixed with clamps and screws. During installation, it is necessary to ensure that there is sufficient heat dissipation space around (at least 50 mm up and down), and avoid being too close to high-voltage lines and high-power equipment (≥ 100 mm).

2.2 Power Wiring and Grounding

Use 2 mm ² or thicker twisted pair cables to connect power terminals, and it is recommended to use isolation transformers to reduce noise.

The chassis grounding (FG) terminal must use independent Class III grounding (grounding resistance<100 Ω) to avoid sharing grounding with other devices.

For inductive loads (relay outputs), it is necessary to parallel freewheeling diodes (DC) or impedance capacitance absorption circuits (AC) at both ends of the load to extend the contact life.

2.3 I/O wiring

Terminal type modules (16 points and below) use M3.0 screw terminals, and it is recommended to use flat terminals (Y-shaped or O-shaped) with wire specifications ranging from 0.5 to 1.25 mm ².

The connector type module (32 points) uses two 20 pin MIL connectors (I and II, opposite directions), which can be self crimped using pre fabricated flat cables (NX70_CBLDC or NX70_CBLTR) or pin type components (NX-PIN20).