Meets the New Frontier. (PDF) In the next few decades, the use of computers and control systems is going to increase greatly. For the foreseeable future, all control systems which are specified by software will be created by programs. Some of these programs will be installed on programmable logic control (PLC) computers, and others will be resident in the system program itself. The programs are used to manage the various tasks of the system. No matter where they are located in the system, the programs must be designed to do the same thing and to do it accurately. If they do not, the results of the system will be erratic and could become seriously harmful.
The performance of the control system depends upon the control program, the PLC or other system program, and the user's ability to modify these programs. The user should not modify the programs, but should be able to easily add and modify new programs, and should be able to completely understand all the information available about any existing programs that are already installed in the system. The control system is designed to accept the user's instructions as commands. For example, the user will first specify the desired speed of the system, and then the speed of the system will be changed in response to the user's command. When commands are used, the process usually includes entering the command as a sequence of numbers, or as a combination of numbers and letters. These commands are called instructions. The numbers and letters that form a command can be entered manually, but the most effective way to enter the instructions is to use a keyboard. For example, to enter the command for the system to increase its speed by five percent, the user would type 95 in this sequence:
(a) An operator inputs the commands to control a system by using a keyboard.
(b) The number of the circuit board is a combination of the status of the three indicators: Red, Green and Yellow.
(c) A zigzag pattern is used to designate the location of a control module.
(d) A square-wave pattern is used to indicate the location of a common connection between two modules.
(e) The waveforms on the screen are as follows: Red, Green and Yellow. The circuit board on which the control system is installed is commonly referred to as a PLC.
(f) The arrows indicate that a signal from the first input is sent to the outputs.
(g) With a key, the operators input the required instructions to the control program of a PLC.
For example, in order to increase the speed of a system, the operator types 95 in the command line, and the system starts to increase the speed.
The PLC (Programmable Logic Control) is the name given to a computer that 0b46394aab