Chapter 4. Ladder Diagram (LD) ProgrammingGFK-2950C February 2018 2014.11 Program Flow FunctionsThe program flow functions limit program execution or change the way the CPU executes theapplication program.Function Mnemonic DescriptionArgumentPresentARG_PRES Determines whether an input or output parameter value was present when thefunction block instance of the parameter was invoked. For example, a parametercan be optional (pass by value).Call CALL Causes program execution to go to a specified block.Comment COMMENT Places a text explanation in the program.End MasterControl RelayENDMCRN Nested End Master Control Relay. Indicates that the subsequent logic is to beexecuted with normal power flow.End of Logic END Provides an unconditional end of logic. The program executes from the first rung tothe last rung or the END instruction, whichever is encountered first.Jump JUMPN Nested jump. Causes program execution to jump to a specified location indicatedby a LABELN. JUMPN/LABELN pairs can be nested within one another. MultipleJUMPNs can share the same LABELN.Label LABELN Nested label. Specifies the target location of a JUMPN instruction.MasterControl RelayMCRN Nested Master Control Relay. Causes all rungs between the MCR and itssubsequent ENDMCRN to be executed without power flow. Up to MCRN/ENDMCRNpairs can be nested within one another. All the MCRNs share the same ENDMCRN.Wires H_WIRE Horizontally connects elements of a line of LD logic, to complete the power flow.V_WIRE Vertically connects elements of a line of LD logic, to complete the power flow.
