The NX102 CPU unit in the Omron NX series machine automation controller is an ideal choice for medium scale motion control and logic control due to its compact 72mm width, built-in EtherCAT master station and dual EtherNet/IP ports, as well as the ability to support up to 32 NX I/O units for expansion. This controller can maintain user programs and hold variables (excluding clock data) without the need for batteries, supports wide temperature operation from -10 to 55 ℃, and has been certified by NK/LR classification society. For on-site engineers, mastering the key points of hardware installation, power system design, fault indicator diagnosis, and regular maintenance can significantly shorten the debugging cycle and reduce unplanned downtime. This article is based on the NX102 hardware user manual (W593) and extracts a complete operation guide from control cabinet layout to battery replacement.
Product Overview and Core Specifications
The NX102 series includes multiple models, with differences in program capacity (5 MB), variable memory (1.5 MB for persistent/32 MB for non persistent), maximum number of control axes (4 to 15 axes), and support for database connections. All models are equipped with:
Built in EtherCAT master station (Class B, compliant with motion control standards, supports linear, daisy chain, branch, and ring topologies)
Dual EtherNet/IP ports (10BASE-T/100BASE-TX, supporting label data links and CIP messages)
NX bus interface, capable of connecting up to 32 NX units (digital I/O, analog, temperature input, position interface, etc.)
SD storage card slot (for backup, recovery, program transfer)
Battery free operation: User programs, set values, and hold variables are stored in non-volatile memory; The clock data is held by a built-in capacitor (approximately 10 days at 40 ℃). If long-term power outage is required to maintain the clock, CJ1W-BAT01 battery can be optionally installed
Main hardware specifications: size 72 × 100 × 90mm, weight 390g, protection level for panel installation (IP20), power supply 24VDC (20.4~28.8V), unit power consumption 5.8W, NX unit power supply capacity 10W, power terminal current capacity 4A.
System configuration and installation steps
2.1 Basic System Composition
A complete NX102 controller system includes:
CPU rack: NX102 CPU unit+NX unit (up to 32)+end cover (NX-END02, provided with CPU)
EtherCAT network: Connect servo drives, encoder input slaves, and EtherCAT slave terminals (such as NX-ECC couplers+NX units) through built-in ports
Upper level connection: Connect Sysmac Studio programming software, HMI or other controllers through EtherNet/IP port
2.2 Installation Preparation
Installation location: Inside the control cabinet, with an ambient temperature of 0-55 ℃, humidity of 10% -95%, no condensation, altitude ≤ 2000m, and pollution level 2.
DIN rail: It is recommended to use OMRON PFP-50N/100N (35mm wide, 7.3mm high) or Phoenix Contact NS 35/7.5 PERF. The guide rail needs to be reliably grounded.
Spacing: Leave at least 20mm of ventilation space at the top and bottom, and space for replacing units on both sides.
Tools: Phillips screwdriver (model XW4Z-00B or SZF 0-0, 4 × 2.5), zip ties, wire cutters, etc.
2.3 Installing CPU Unit and NX Unit
Fix the DIN rail to the backplate (M4 screws, torque 1.2N · m, spacing ≤ 105mm).
Confirm that the DIN rail hook on the back of the CPU unit is in the unlocked position (pulled up).
Press the CPU unit towards the guide rail and lock the hook downwards. Confirm firmness.
Remove the end cap on the right side of the CPU (installed at the factory). Slide the first NX unit along the guide rail so that its upper and lower guide hooks engage with the CPU unit, and press it towards the guide rail until the hook locks. Repeat until all NX units are installed.
Install the end cover to the right side of the last NX unit, slide it in and lock it.
Install end plates (PFP-M) at both ends of the rack to prevent lateral movement of the unit.
Attention: The NX unit connector contains signal pins, do not touch or contaminate them; Do not write or paste labels in the prohibited area of the unit casing (near the connector) to prevent foreign objects from entering the connector and causing poor contact.

Power system design
The power system of NX102 is divided into two channels: Unit Power and I/O Power.
3.1 Unit Power Supply
Powered by an external 24VDC power supply, connected to A1/B1 (24V) and A3/B3 (0V) of the CPU unit terminal block. Two 24V terminals and two 0V terminals are connected in parallel internally and can be used for wiring to subsequent additional power supply units.
The terminal capacity is 4A, and the CPU unit itself consumes 5.8W, while providing up to 10W of NX unit power (via NX bus) to the NX unit.
If the total power consumption of the NX unit exceeds 10W, an additional NX unit power supply unit (NX-PD1000, etc.) must be inserted in the middle, which takes power from the outside and supplies power to all units on the right side. Attention: Adding NX unit power supply unit will cut off the power supply from the left unit (electrical isolation).