OMRON NX502 CPU Unit Hardware Installation and Maintenance Guide

OMRON NX502 CPU Unit Hardware Installation and Maintenance Guide

In large-scale machine control and factory IoT applications, the I/O capacity and communication bandwidth of traditional PLCs often become bottlenecks. As a high-end model of the NX series, the Omron NX502 CPU unit not only supports up to 63 NX I/O units, but also introduces a high-speed X bus that can connect up to 4 X bus units (such as EtherNet/IP units) and build up to 10 independent EtherNet/IP networks. It has built-in Gigabit Ethernet ports, database direct connection services, and OPC UA servers, making it a controller platform for Industry 4.0 and IoT. This article is based on the NX502 hardware user manual and provides engineers with a full process guide from installation and wiring, power design to fault diagnosis.

Product model and core specifications

The NX502 series includes multiple models, with the difference being the maximum number of control axes and memory capacity. All models come with 80MB program capacity, 4MB persistent variable memory (power on hold), and 256MB non persistent variable memory.

Model Maximum Control Axis Number (Actual Axis Number) Database Connection

NX502-1700 256 axis (256 axis) support

NX502-1600 128 axis (128 axis) support

NX502-1500 supports 128 axis (64 axis)

NX502-1400 64 axis (32 axis) support

NX502-1300 32 axis (16 axis) support

Hardware specifications: External dimensions 135 × 100 × 120mm, weight 920g. Power supply 24VDC (20.4~28.8V), unit power consumption 18.3W, NX unit power capacity 10W, X bus unit power capacity 50W (directly powered from the unit power supply, no external power supply required). Terminal current capacity 4A. Built in 1 EtherCAT port (100BASE-TX) and 2 EtherNet/IP ports (1000BASE-T, backward compatible).

Key features:

X bus: It can connect EtherNet/IP units such as NX-EIP201, with each unit providing dual ports and a total bandwidth higher than the NX bus.

Database connection: Supports SQL Server, Oracle, MySQL, PostgreSQL, and can interact with the database through encrypted communication.

Battery free operation: User programs, variables, and event logs are stored in non-volatile memory; The clock is held by a capacitor (approximately 10 days at 40 ℃), and the optional battery can extend the holding time.

System configuration and hardware installation

2.1 Rack composition

The NX502 CPU rack is divided into two parts:

X bus side (left side): Connect up to 4 X bus units (such as EtherNet/IP units). The X bus unit is directly powered by the CPU and has a total capacity of 50W.

NX bus side (right side): up to 63 NX units (digital I/O, analog, temperature, position interface, etc.) can be connected. The NX unit is powered by the CPU or an additional NX unit power supply unit, with a total capacity of 10W.

End cap: The right end must be equipped with an end cap (NX-END02, provided with the CPU); If the X bus unit is not connected to the left side, keep the factory protective cover.

2.2 DIN rail installation

Recommended guide rail: OMRON PFP-50N/100N (height 7.3mm) or Phoenix Contact NS 35/7,5 PERF (7.5mm).

Fixed screws: M4 (torque 1.2N · m) or M6 (torque 5.2N · m), spacing ≤ 105mm.

Installation steps:

Pull up the DIN rail hook on the back of the CPU unit to the unlock position.

Press the unit towards the guide rail and lock the hook downwards.

When installing the X bus unit, first release its upper and lower sliders and hooks, slide in from the left side to connect with the CPU, and then lock the sliders and hooks.

Install NX unit: slide in from the right side, engage the guide hook and press it towards the guide rail until the hook is locked.

Install end caps on the far right and end plates (PFP-M) at both ends of the rack to prevent lateral movement.

Attention: For CPUs and NX-EIP201 manufactured on or before August 27, 2024, if 3 or more X-bus units are installed, anti vibration measures must be taken (consult Omron representative).

Power system design

The power supply of NX502 is divided into three channels: unit power supply (for CPU, internal circuits of NX unit, and X bus unit), NX unit I/O power supply (for field circuits and external devices of NX unit), and X bus unit does not require additional I/O power supply.

3.1 Unit power supply calculation

Formula: Required unit power capacity=(CPU power consumption+total power consumption of X bus unit+total power consumption of NX unit)/NX unit power efficiency (80%)

Example (Configuration: CPU NX502-1500 18.3W+1 EtherNet/IP unit 8.1W+1 additional I/O power supply unit 0.85W+4 digital input units 0.9W × 4+3 relay output units 1.2W × 3):

Total power consumption (internal circuit)=18.3+8.1+0.85+3.6+3.6=34.45W

Required power capacity=34.45W/0.8 ≈ 43.1W

Attention: If the total power consumption of the NX unit exceeds 10W, an additional NX unit power supply unit (NX-PD1000, etc.) must be inserted on the right side, which takes power from the outside and supplies power to subsequent units.

3.2 I/O Power Supply Design

Some NX units (such as digital I/O) require I/O power to drive field sensors or loads. The I/O power supply can be powered through the NX bus (requiring an additional I/O power supply unit, such as NX-PF0630) or directly supplied externally.