OMRON NX series system unit power configuration and troubleshooting

Gently pull the wire to confirm a secure connection.

Common error: Inserting the release hole vertically (90 °) will damage the terminal; Excessive force (over 30N) can cause the spring to deform; Rotating or twisting the screwdriver during insertion can also damage the terminal.

5.4 Secure Wires

When the wire diameter is thick or subjected to vibration, a cable tie (width ≤ 4mm, thickness ≤ 1.5mm) can be used to pass through the tie hole at the bottom of the terminal and tie the cable to the terminal seat to reduce the tension of the terminal on the wire.

Precautions for installation and disassembly

6.1 Installing NX Unit

The DIN rail must be installed first.

Two units are connected to each other through Unit Hookup Guides, and then pressed towards the DIN rail until the DIN Track Mounting Hook locks with a "click" sound.

It is strictly prohibited to install or dismantle units with electricity.

Do not touch the pins of the NX bus connector (located on the left side of the unit) to avoid contamination or electrostatic damage.

6.2 Disassembling NX Unit

Use a flat screwdriver to lift the DIN rail mounting hook upwards.

Then grab the protrusions for removing the unit on both sides with your hands and pull the unit forward. If there are other units on the right side that need to be disassembled, it is recommended to pull them out together with all the units on the right side, otherwise it is difficult to remove the middle unit separately.

6.3 Installation direction restrictions

When the system unit is connected to the CPU unit or communication control unit, it is only allowed to be installed vertically upright (with ventilation openings facing up/down).

When connected to the EtherCAT coupler as a slave terminal block, six directions (upright, flat, inverted, etc.) are allowed, but it should be noted that the output power of NX-PD1000 will decrease with increasing ambient temperature when not installed upright. For example, when installed upright at 45 ℃, it can still output 10W, but when installed lying flat at 45 ℃, it may only output about 6W.

Diagnosis and troubleshooting of indicator lights

7.1 TS indicator light (shared by all system units)

This indicator light (green/red) displays the status of the NX unit itself and the communication status with the higher-level unit (CPU or coupler).

TS LED status meaning countermeasures

Green is constantly on and running normally. I/O refresh is ready and working normally

Green slow flashing (2s interval) waiting for completion during initialization, restart, or project download, usually without intervention

If the hardware malfunction or watchdog error persists after re powering on the red light, replace the unit

Red flash (1-second interval) NX bus communication error check for loose connections between units and proper installation of units

The power supply of the unlit unit is not powered, or the unit is restarted/waiting for initialization to check the power wiring and 24VDC supply of the unit; If the power supply is normal and does not light up for a long time, the unit may be damaged

7.2 UNIT PWR indicator light (NX-PD1000 only)

Green constantly on: The unit power supply is normal.

Not lit: The unit power supply has not reached or the voltage exceeds the range of 20.4~28.8V. Check the external 24V power supply and wiring.

7.3 I/O PWR indicator light (NX-PF0630/0730 only)

Green constantly on: I/O power supply is normal.

Not lit: The I/O power supply has not reached or the voltage exceeds the range of 4.5~28.8V. Check the external I/O power supply and wiring.

7.4 Analysis of Typical Fault Cases

Case 1: All indicator lights on the NX unit on the right side of the CPU rack are not lit.

Reason: The unit power supply is not transmitted through the NX bus. It may be due to improper installation or damage of NX-PD1000, or insufficient unit power capacity of the CPU unit.

Check: Measure whether the UV/UG terminals of the CPU unit have 24V. If not, check the external power supply. If so, check if the UNIT PWR indicator light of NX-PD1000 is on. If it doesn't light up, check its UV/UG wiring. If it lights up but the right unit still has no power, it may be due to poor contact of the NX bus connector.

Case 2: The I/O PWR indicator light is on, but a certain analog input unit reading is abnormal.

Reason: The I/O power supply voltage exceeds the required range of the analog module (for example, a 24V sensor is connected to a 5V power supply segment).

Check: Measure the voltage between the IOV and IOG terminals of the module. If the voltage input from the additional I/O power supply unit does not match, it indicates that there may be an I/O power supply connection unit that has mistakenly connected to a different voltage.

Case 3: The TS indicator light flashes red and Sysmac Studio reports a "Non volatile Memory Hardware Error" (event code 00200000 hex).

Reason: Hardware failure of non-volatile memory in the unit.

Countermeasure: Try powering on or restarting the NX bus (via software reset) first. If the fault persists, the NX unit must be replaced. This fault cannot be fixed through the user program.

Case 4: The unit power supply is normal, but the right unit still cannot be recognized.