Description
The time required for the action of mechanical equipment in their respective steps is generally constant, even if the change is not significant. Therefore, these times can be used as a reference. When the programmable controller sends an output signal and the corresponding external executing mechanism starts to act, a timer timer is activated to set a value that is about 20% longer than the normal duration of the action. For example, if an actuator (such as an electric motor) operates for 10 seconds under normal conditions, the components it drives will activate the limit switch and send a signal to end the action. If the action time to be executed exceeds 12 seconds (i.e. the set time of the corresponding timer), the programmable controller has not yet received the action end signal, and the normally open contact of the timer delays the connection to send a fault signal. This signal stops the normal circulation program, starts the alarm and fault display program, enabling operators and maintenance personnel to quickly identify the type of fault and take timely measures to eliminate the fault.
During normal operation of the system, there is a definite relationship between the input and output signals of the programmable controller and internal signals (such as the status of auxiliary relays). If an abnormal logic signal occurs, it indicates that a fault has occurred. Therefore, it is possible to develop abnormal logical relationships for common faults. Once the abnormal logical relationship is in the ON state, it should be handled as a fault. For example, during the movement of a certain machine, two limit switches are activated one after another, and these two signals will not be in the ON state at the same time. If they are both ON, it indicates that at least one limit switch is stuck and should be shut down for processing. In the ladder diagram, the normally open contacts of the input relay corresponding to these two limit switches are connected in series to drive an auxiliary relay that represents a limit switch fault.
Model recommendation:
AM811F
AM54072
AM801F
AM801F 3BDH000040R1
AM810F-Z
AM811F 3BDH000050R1
AM811F-Z
AM895F
AM895F 3BDH000044R1
AI835AI835
AI843
AI843 3BSE028925R1
AI843-eA
AI845 3BSE023675R1