It reduced human error and provides continues result of process or system. plc save fuel, cost, processing material, labor and increased production. below are some common question for plc asked in interview.

user function block designed to perform a specific task and can be called multiple times throughout a program, reducing redundancy and improving maintainability. Each plc programming have standard block like timer, counter, arithmetic, comparison block but user function block are made by programmer for use multiple time l

widget and tag permission allows only specific user to access widget action, event or wright value on tag. when you add wright permission for tag than only assigned user change value or wright value of tag. all other user not access these tag. security features is very important for industrial control system

user management in abb hmi with abb panel builder 600,abb hmi have user management action in user management you can add, remove user, user password will reset during runtime. before user management enable security features of hmi. in this article we use action to add, remove, login, logout and reset password of user using abb panel builder and abb hmi cp 600.

security features restrict unauthorized access of your hmi. in abb cp600 hmi have security features. you add security for your widget component, data transfer access alarm reset, alarm acknowledgment, ON or OFF process etc.abb hmi have role based access control that allows user for different role

functional block diagram have up counter, down counter and up down counter blocks. up counter is an incremental counter, down counter is a decremented counter and up down counter perform both action when particular counter input bit is set. up counter and down counter have fixed input and output.

Page in a hmi is a visual display or interface which are used to design for user in a Human machine interface (HMI). HMI have collection of different pages each pages design for different purpose. in hmi page design for specific task like control a process, alarm, trend, navigation, process overview, hmi setup, hmi communication configuration etc.

these events set and configured in panel builder. for example if you want to start a motor by pressing a button than you can set an event set bit. once the button is pressed than bit is set to tag.

functional block diagram have on delay timer TON and OFF delay timer TOF. timer are most important instruction in plc programming. an on delay timer on output when elapsed time reached to preset value. off delay timer set output off when input of timer is changed from true to false and preset time is equal to elapsed time.

functional block diagram is a graphical representation programming of plc. each block of FBD have different operation. logical operator or Boolean operator in functional diagram are AND, OR and XOR. these Boolean operator have two inputs or three inputs.