A PLC's Master Control Relay (MCR) is defined by experts as a unique relay utilized in ladder logic programming to regulate the operation of several rungs or parts of a ladder diagram. In essence, it uses certain conditions to determine whether to enable or disable particular software sections. All rungs between the MCR and the associated end instruction are executed when the MCR is turned on. These rungs cannot run if the MCR is deactivated because they are circumvented. Large portions of a program can be controlled with a single condition because to this functionality, which enhances program organization and efficiency.
In first photo, Master Control Relay is used as normally opened coil, called Master Coil. As you can see when the "Start" is triggered, Master Coil will be closed contact and executes the multiple rungs. If "Stop" is triggered, Master Coil is disable the execution of the other rungs.
Similarly, in second figure, I've used Omron PLC and i used the instruction of Master Control Relay. When Trigger_1 is On, MC allows the execution of the rungs. However, if Trigger_1 is Off, it won't allows the execution. You can use whatever you like but if the program became complex, we have to use the provided instruction of Master Control Relay depend on the manufacturer. It can handle and easy to detect during the maintenance.
Reference : Sanfoundry, Indmallautomation
Comments
Post a Comment