CNC Controller Keyboard ERR

There is Keyboard ERR displayed on the GSK928TE CNC controller screen after turn on the CNC machine power, press any key but could not enter the system.

It could be checked by below steps:

1-      Check if there is any key in short circuit?

2-      The outer switch in short circuit or not?

3-      Any wrong wiring of the input signal cables?

(From http://www.CNCmakers.com) 

Check above one by one, we found the Start Circle key was connected as Normally-Close, which detected by the CNC controller and caused the Keyboard ERR alarm, change it to Normally-Open and the problem solved.