Alarming News! Okuma Alarm Codes You May Not Know About

What happens when an alarm goes off on your machine tool? Is it a routine fix? Or is it something more complex?

We can help you get to the bottom of it.

Okuma alarm codes quickly notify operators who use the OSP-P300 or the new OSP-P500 if something’s gone wrong — a programming error, a machine malfunction, a tool issue — so they can respond more effectively and efficiently.

Understanding what the alarm codes mean, especially those that appear less frequently, can be the difference between business as usual and serious consequences, like machine tool damage and downtime. Keep reading to learn about eight Okuma alarm codes you shouldn’t ignore, why they appear, and how to prevent their occurrence in the future.

The following Okuma alarm codes can appear on machine tools with OSP-P300 and OSP-P500.

1151 MCS INVERTER UNIT DETECTED AN ERROR

This alarm usually indicates an issue with an inverter — a defective inverter control board, motor over current, low or high voltage, or a shorted motor — which can significantly impact machine operation and performance. We’ve seen instances in which a faulty motor takes out an entire drive unit, resulting in both needing to be replaced. And, in one case, we replaced the inverter, MCS power supply, and servo controller because the source of the alarm was a damaged encoder cable at the motor.

721 DEVICE NET ERROR

This alarm can occur after an option is added to a machine tool or new software has been installed into the OSP control. Causes of this alarm include poor electrical connections, incorrect switch settings, or I/O mapping that may not have the necessary IOs mapped for the newly installed option. This alarm is more frequently seen on the GENOS lathe products after option installation. The GENOS lathe software incorporates an additional DVD that contains the I/O mapping software. Failure to install this additional DVD triggers a 721 alarm.

758 SAFETY I/O ERROR

This alarm occurs when a problem develops in the safety IO link, often caused by a shorted solenoid or a switch that is exposed to coolant contamination and shorts out. Damage can happen to an IO board during shortages. In most cases, the code that follows this alarm will point the repair technician to the proper input or output location. However, it is sometimes difficult to identify the slot or connector number, necessitating in-depth troubleshooting.

812 ERROR DURING INITIALIZATION OF MCS

This alarm indicates that the OSP control sees a discrepancy in the serial link of the MCS system during control boot-up. First, look for a faulty drive unit, improper controller ID address setting, or an issue with the servo cabling connections. If these components are intact, the alarm may stem from troubleshooting that was administered previously or miswiring in the serial link of the MCS system. A trained Okuma service technician can help identify the source of the alarm code and make the right repair(s).

4085 FAN MOTOR ERROR ON PANEL COMPUTER UNIT

This alarm code notifies operators that the CPU fan or the power supply fan is not operating at the specified threshold speed set by the control. A technician can visually inspect the fans to see if they’re plugged in correctly and properly rotating. If one or both fans rotate slowly, replacements may be necessary. If a fan rotates at its correct speed, the panel computer would need to be inspected to find the root cause.

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The following Okuma alarm codes are specific to machine tools with OSP-P500.

0945 MEMORY BOARD/BATTERY LIFE

This alarm indicates the Uninterruptible Power Supply (UPS) battery for the control is near the end of its life, which is approximately six years. When this alarm occurs, you should immediately change the battery for a fresh one. The purpose of this battery is to back up parameters when the machine is powered down correctly. If the battery is not replaced when the alarm occurs and the battery reaches its end of life, all parameters in the control could be lost.

As good practice, also replace the coin battery on the HMI/PNC board that is used to back up the date and time when you replace the UPS battery.

1181 MCS DIFF OVER

This is another alarm that needs special attention. When the axis cannot move where it is commanded to go, a mechanical issue may be at fault. Broken tools, chip buildup, or defective parts may also be to blame. And occasionally, a Diff Over alarm is caused by a damaged servo amp, cable, or motor. When this alarm occurs, don’t ignore it by pressing the rest button. Instead, alert your Okuma distributor or service technician who can determine and eliminate the root cause.

2160 MCS SUPPLY VOLTAGE FLUTTER

This alarm occurs when the supplied voltage is abnormally high or low, notifying operators that the power supplied to the machine tool cannot maintain proper voltage levels needed for operation. This alarm will appear most often during heavy acceleration or deceleration of the main spindle because this is when the CNC draws the most power. To dismiss this alarm, supply the correct power to all CNC equipment based on the KVA rating of the machine. Also, check for loose connection of power lines.

CONCLUSION

Okuma alarm codes should never be ignored; only prioritized. And troubleshooting an alarm — which should be the first step taken when one appears — requires a technician with proper training, knowledge of the OSP control, and experience with the associated electrical systems. With each condition we encounter and each solution we create saved to an internal knowledge base for reference anytime, the skilled Okuma CARE team is ready to help you avoid expensive repairs and downtime when any alarm occurs.

Special thanks to Brian O’Dell, Support Center Tech, Okuma America Corporation, for providing this article.