6.13 Impact on the program during monitoring
During monitoring, you can use the right button on the mouse to call up a menu of some elements of ladder diagram. Menu that appears when we click on location where address of some bit is positioned, contains the following elements:
Force Set - used for permanent forced set up of bit status to ON
Force Reset - used for permanent forced set up of bit status to OFF
Cancel - cancels out the forced status
Set (1) - used for a brief change of bit status from OFF to ON status
Reset (0) - used for a brief change of bit status from ON to OFF status
Cancel All - cancels out forced status of all bits
With the help of these options, status of bits can be changed, word contents in controller memory can also be changed, and all or some of the earlier forced settings can be cancelled out. The concept of forcing entails forced set up of some input/output to ON or OFF status for program reevaluation. At the moment when PLC leaves monitoring regime, data on forced bits and words is lost. Simultaneous forcing and evaluation of contents of a greater number of dimensions, and Data Set Bar is used for this, usually found at the bottom of the monitor (see previous picture). Editing as well as defining an area in Data Set Bar is accomplished with a double click following which a corresponding message window appears, and we write here address for the bit whose status we are following.