The so-called offline detection is: when the CNC machining center system presents problems or demand diagnosis, often we need to stop processing detection. The purpose is to CNC machining center can continue to work.

In order to CNC machining center fault cleaning, we often need to repair the system and fault positioning, so the need to reduce the fault to a certain range, we can more accurately identify the cause and stop the follow-up maintenance work.

Early CNC installation is the use of special diagnostic paper tape to CNC system offline diagnosis. Diagnostic tape to provide the demand data, and to diagnose tape content when read in CNC system RAM, disposal of the device in the system according to the response of output data to stop, whether there is something wrong with to identify system and must be wrong so far, the recent engineer panel of CNC system is used, modified or dedicated CNC system testing installation to stop testing, modern CNC system, the maintenance diagnosis more lunch.

Due to the rapid development of computer technology and network communication technology, the self-diagnosis system is also being developed in two directions: on the one hand, the artificial intelligence expert fault diagnosis system is being developed by relying on system resources; on the other hand, the self-diagnosis system of network telecommunication is being developed by using network technology.