
1.OVERVIEW B-63494EN/02
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1.3 BASIC PRINCIPLE OF DUAL CHECK SAFETY
1.3.1 Features of Dual Check Safety
Dual Check Safety function has the following features.
• Two-channel configuration with two or more independent CPUs
• Cross-check function for detecting latent errors
Detection
A servo motor detector signal is sent via the servo amplifier and is
applied to the CNC through the FSSB interface. Then, it is fed to two
CPUs: a CNC CPU and a servo CPU.
A spindle motor detector signal is sent via the spindle amplifier and is
applied to the CNC connected through the serial interface. Then, it is
fed to two CPUs: a CNC CPU and a spindle CPU.
Evaluation
The safety function is monitored independently by a CNC CPU and
servo CPU or by a CNC CPU and spindle CPU. Each CPU
cross-checks data and results at certain intervals.
Response
If the monitoring function detects an error, the CNC CPU and the
servo/spindle CPU switch off the MCC via independent paths to shut
off the power to the feed axis and spindle.