MapleLogic Terms
| Term | Definition |
|---|---|
| Buffer Memory | A temporary storage area used to hold data during transfers between devices or program elements. In PLCs, buffer memory is often used for storing input/output values, communication data, or intermediate results during execution. |
| Coil | An output symbol in ladder logic representing an energized output device, such as a relay coil. |
| Contact | Symbolic representation in ladder logic that replicates the behavior of a physical relay contact, controlling the flow of current based on specific conditions. |
| Data Register | A memory location used to store values such as numerical values, counters, timers, or intermediate calculations. |
| Deenergize (Power OFF) | The action of removing power from a component, typically to deactivate or stop a process. |
| Duty Cycle | The proportion of time a signal or system is active compared to the total time of one cycle, often expressed as a percentage. |
| Energize (Power ON) | The action of applying power to a component, typically to activate or initiate a process. |
| Execution | The action of running or carrying out a command, instruction, or sequence within a program. |
| Execution Condition | A specific condition or set of conditions that must be met for an instruction, function, or program block to execute. |
| Falling Edge | The transition of a signal or input from a high state (1) to a low state (0). This is often used to detect when an event just ends. |
| Function Block Diagram (FBD) | A graphical programming language that represents functions and their data flow using interconnected blocks. |
| Input | A signal or data received by the PLC from an external source, such as sensors, switches, or user devices. Inputs are read during the scan cycle and used to determine program logic execution. |
| Instruction | A command in a program that performs a specific operation. |
| Instruction List (IL) | A text-based programming language consisting of a list of instructions executed sequentially. |
| Interpolation | The process of estimating intermediate values between two known data points or states in a sequence. |
| Inversion | A logical operation that reverses the state of a signal, turning a true (1) signal into false (0) or a false (0) signal into true (1). |
| Ladder Diagram (LD) or Ladder Logic | A graphical programming language resembling electrical relay logic diagrams. |
| Latch | A mechanism that maintains its state (on or off) even after the activating input signal is removed, until reset. |
| Logic Gate | A basic building block in digital logic, used to perform logical operations (AND, OR) on one or more inputs to produce an output. |
| Negative Transition-Sensing Contact | A one-shot contact that activates only during the transition from a high (1) to low (0) state, responding only to the negative (falling) edge. |
| Non-Volatile Memory | A type of memory that retains stored data even when power is turned off. |
| Normally Closed Contact | A contact that remains closed (conductive) when inactive and opens (non-conductive) when activated, stopping current flow. |
| Normally Open Contact | A contact that remains open (non-conductive) when inactive and closes (conducts) when activated, allowing current to pass. |
| One-Shot | Contact or instruction type that triggers only once when the execution condition is met, regardless of how long the execution condition remains true. |
| Output | A signal or command sent from the PLC to external devices such as relays, motors, indicators, or actuators. Outputs are updated based on the logic evaluation after all instructions are executed in the scan cycle. |
| Pascal | A high-level programming language developed in 1970 by Niklaus Wirth, designed to encourage good programming practices and structured programming. |
| Positive Transition-Sensing Contact | A one-shot contact that activates only during the transition from a low (0) to high (1) state, responding only to the positive (rising) edge. |
| Read | The action of retrieving data or input values from a source. |
| Rising Edge | The transition of a signal or input from a low state (0) to a high state (1). This is often used to detect when an event just begins. |
| Scan | The process of sequentially reading inputs, executing the program logic, and updating outputs in a control system, typically occurring in cycles. |
| Scan Cycle | The continuous loop executed by a PLC that includes reading all inputs, processing the user program, and updating all outputs. Each complete pass is called one scan and determines the PLC’s response time to input changes. |
| Sequential Function Chart (SFC) | A graphical programming language which organizes processes into steps and transitions to represent the sequence of operations. |
| Step | A discrete stage or part of a process sequence. |
| Structured Text (ST) | A high-level, text-based programming language used for PLC programming, defined in the IEC 61131-3 standard. MapleLogic uses Pascal for Structured Text. |
| Subroutine | A smaller, reusable section of logic within a larger program, designed to perform a specific task and called as needed within the main program. |
| Volatile Memory | A type of memory that loses all stored data when power is turned off. |
| Write | The action of sending or storing data or values to a destination. |