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ECT 464

ECT 464. Lecture 4b Special Functions. Special Functions. One Shot (ONS) (OSR) SLC500 triggers a one time event activates on false to true transition rung must go false again to reset allowed to use one OSR per output in a rung do not place input conditions after the OSR

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ECT 464

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  1. ECT 464 Lecture 4b Special Functions

  2. Special Functions • One Shot (ONS) (OSR) SLC500 • triggers a one time event • activates on false to true transition • rung must go false again to reset • allowed to use one OSR per output in a rung • do not place input conditions after the OSR • uses a bit location to store last state

  3. Special Functions • One Shot Rising (OSR) • triggers a one time event • activates on false to true transition • rung must go false again to reset • allowed to use one OSR per output in a rung • do not place input conditions after the OSR • uses a bit location to store last state • Activates output bit

  4. Special Functions • One Shot Falling (OSF) • triggers a one time event • activates on true to false transition • rung must go true again to reset • allowed to use one OSF per output in a rung • do not place input conditions after the OSF • uses a bit location to store last state • Activates output bit

  5. Special Functions • Label (LBL) • Target of jump instruction • Must be first instruction of rung • 256 labels in each subroutine (SLC) • 1000 labels in each subroutine (M1000)

  6. Special Functions • Master Control Reset (MCR) • Acts on rungs between start and end fence • When off, ignores inputs, and de-energizes all outputs in the zone • When on, inputs and outputs treated normally • Latches, retentive timers, and counters remain in their last state • Must end zone with unconditional MCR • Cannot nest MCR’s • Always place MCR as last instruction on rung

  7. Special Functions • Jump (JMP) • When true, skips to the rung with the LBL instruction and continues executing • When false, doesn’t do anything • Can jump forward and backward • Can jump to the same label from several JMP instructions • Do not jump into a MCR zone • Not between program files

  8. Special Functions • Temporary End (TND) • Stops processor from scanning the rest of the rungs • Used to debug a program • Used to stop the execution of part of a main program or subroutine

  9. Special Functions • Suspend (SUS) • Sends PLC into idle mode • All outputs de-energized • Used with Suspend ID number

  10. Special Functions • Subroutine (SBR) • Marks the beginning of a file • Optional use

  11. Special Functions • Jump to Subroutine (JSR) • Used to execute a subroutine and then return • Saves memory • Nest 8 levels deep • File number 3-255 (SLC or M1500) • File number 4-15 (M1000)

  12. Special Functions • Return (RET) • Marks the end of a subroutine • Can be conditional (SLC) • Optional Use (END works as well) • Can return a value (SLC)

  13. Special Functions • End (END) • Marks the end of a file

  14. Special Functions • Immediate Input with Mask (IIM) • Update data prior to normal scan • Mask of 1 passes • Specify input word • Embedded I/O only

  15. Special Functions • Immediate Output with Mask (IOM) • Update outputs prior to normal scan • Mask of 1 passes • Specify output word • Embedded I/O only

  16. Special Functions • I/O Refresh (REF) • Executes a new I/O scan in middle of execution • Can also do communications

  17. Next Class • I/O Scans and memory layout • PLC Modes

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