Programming in Boolean
The preceding example circuit was developed for one specific type of programmable controller. It was in- tended as an example of how to develop and enter a pro- gram into the logic of the CPU using a programmable terminal similar to the one shown in Figure 54 – 4. There may be times when it is necessary to use a small programming device that is hand held or that attaches directly to the CPU when entering a program. A unit of this type is shown in Figure 54 – 11. This programming unit can be used with the SERIES ONE group of programmable controllers manufactured by GE Fanuc Automation. The following program will be developed for entry into the SERIES ONE using the handheld programmer.
Developing the Program
The following program will be used as a trouble annunciator: A pressure switch is to be connected to the input of a programmable controller. When the pressure rises to a preset point, an audible alarm will be sounded and a warning light will flash off and on. When the operator acknowledges the trouble, the audible alarm will be silenced, but the warning light will continue to flash on and off until the pressure returns to a safe level.