Mitsubishi Electronics FX1S manual What is STL, SFC And IEC1131 Part 3?, General note

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FX Series Programmable Controllers

STL Programming 3

3.STL Programming

FX1S

FX1N

FX2N

FX2NC

This chapter differs from the rest of the contents in this manual as it has been written with a training aspect in mind. STL/SFC programming, although having been available for many years, is still misunderstood and misrepresented. We at Mitsubishi would like to take this opportunity to try to correct this oversight as we see STL/SFC programming becoming as important as ladder style programming.

3.1What is STL, SFC And IEC1131 Part 3?

The following explanation is very brief but is designed to quickly outline the differences and similarities between STL, SFC and IEC1131 part 3.

In recent years Sequential Function Chart (or SFC) style programming (including other similar styles such as Grafcet and Funktionplan) have become very popular through out Europe and have prompted the creation of IEC1131 part 3.

The IEC1131 SFC standard has been designed to become an interchangeable programming language. The idea being that a program written to IEC1131 SFC standards on one manufacturers PLC can be easily transferred (converted) for use on a second manufacturers PLC.

STL programming is one of the basic programming instructions included in all FX PLC family members. The abbreviation STL actually means STep Ladder programming.

STL programming is a very simple concept to understand yet can provide the user with one of the most powerful programming techniques possible. The key to STL lies in its ability to allow the programmer to create an operational program which ‘flows’ and works in almost exactly the same manner as SFC. This is not a coincidence as this programming technique has been developed deliberately to achieve an easy to program and monitor system.

One of the key differences to Mitsubishi’s STL programming system is that it can be entered into a PLC in 3 formats. These are:

Ι) Instruction - a word/mnemonic entry system

ΙΙ) Ladder - a graphical program construction method using a relay logic symbols

ΙΙΙ) SFC - a flow chart style of STL program entry (similar to SFC)

Examples of these programming methods can be seen on page 2-1.

General note:

•IEC1131-3: 03.1993 Programmable controllers; part 3: programming languages. The above standard is technically identical to the ‘Euro-Norm’

EN61131-3: 07.1993

3-1

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Contents Programming Manual Page Foreword FX Series Programmable ControllersFX Series Programmable Controllers FAX Back Combined Programming Manual J FX Series Programmable Controllers Software Warnings Hardware WarningsFX Series Programmable Controllers Contents STL Programming Applied Instructions Rotation And Shift Functions 30 to External FX Serial Devices Functions 80 to Execution Times And Instructional 10-1 Viii FX Series Programmable Controllers Chapter Contents Overview IntroductionWhat do You Need to Program a PLC? What is a Programmable Controller?Current Generation CPU all versions Special considerations for programming equipmentManual name Number FX Base Unit Hardware Assocciated ManualsManual name Number FX DU, GOT and DM units Memo Basic Program Instructions FX Series Programmable ControllersBasic Program Instructions Detailed device information What is a Program?Outline of Basic Devices Used in Programming Example How to Read Ladder LogicProgram example Load, Load InverseOUT instruction Out Timer and Counter VariationsDouble Coil Designation Use of dual coilsLast coil effect Peripheral limitations And, And InverseORI Or, Or InverseSingle Operation flags M2800 to M3071 Load Pulse, Load Trailing PulseLDF ANF OUT Pulse, And Trailing PulseORF ORB Or Pulse, Or Trailing PulseSequential processing limitations Or BlockBatch processing limitations ANB BlockMPS, MRD and MPP usage 13 MPS, MRD and MPPMultiple program examples MCR Master Control and ResetNested MC program example Resetting timers and counters Set and Reset16.1Basic Timers, Retentive Timers And Counters Timer, Counter Out & ResetRetentive timers Availability of devices Bit countersNormal 32 bit Counters High Speed CountersLeading and Trailing Pulse PLFUsages for INV InverseNo Operation No OperationProgram scan 20 EndMemo STL Programming FX Series Programmable ControllersSTL Programming General note What is STL, SFC And IEC1131 Part 3?Look Inside an STL How STL OperatesEach step is a program Combined SFC Ladder representation How To Start And End An STL ProgramEmbedded STL programs Activating new statesReturning to Standard Ladder Initial StepsTerminating an STL Program Moving Between STL Steps Using SET to drive an STL coilOut is used for distant jumps Using OUT to drive an STL coilOUT is used for loops and jumps Basic Notes On The Behavior Of STL programs Rules and Techniques For STL programsT001 K20 K50 Method 2 Special Single Pulse Flags Single Signal Step ControlMethod 1 Using locking devices Restrictions on using applied instructions Restrictions Of Some Instructions When Used With STLUsing ‘jump’ operations with STL STL OUT SET Using STL To Select The Most Appropriate ProgramLimits on the number of branches Using STL To Activate Multiple Flows SimultaneouslyLimits on the number of branches Instruction Format General Rules For Successful STL BranchingGeneral Precautions When Using The FX-PCS/AT-EE Software Simple STL Flow Programming ExamplesSET STL Identification of normally closed contactsSelective Branch/ First State Merge Example Program Points to noteFull STL flow diagram/program Advanced STL Use Devices in Detail FX Series Programmable ControllersDevices in Detail Inputs Configuration detailsAvailable devices Device MnemonicAlias O/P OutputsDevice Mnemonic Y General Stable State Auxiliary Relays Auxiliary RelaysDevice Mnemonic M External loads Battery Backed/ Latched Auxiliary RelaysSpecial Single Operation Pulse Relays Special Diagnostic Auxiliary RelaysGeneral Stable State State Relays State RelaysDevice Mnemonic S PLC FX 1S FX 1N FX 2N Battery Backed/ Latched State RelaysMonitoring STL programs Assigned statesSTL/SFC programming IST instructionAnnunciator Flags Jumping to the end of the program PointersDevice availability Device Mnemonic PAdditional applied instructions Interrupt PointersNested levels Pointer positionInput Interrupts Timer InterruptsRules of use Disabling high speed counter interrupts Driving special auxiliary relaysAdditional notes Disabling Individual InterruptsConstant H Constant KDevice Mnemonic K Example device usage N/ADevice Mnemonic T TimersTimer accuracy Driving special auxiliary coils General timer operationSelectable Timers Retentive Timers Using timers in interrupt or ‘CALL’ subroutinesTimers Used in Interrupt and ‘CALL’ Subroutines Internal timer accuracyTimer Accuracy ConditionCounters Setting ranges for countersHigh speed counters Device Mnemonic CGeneral/ Latched 16bit UP Counters Battery backed/latched countersGeneral/ Latched 32bit Bi-directional Counters Battery backed/ latched countersSelecting the counting direction Further uses None Basic high speed counter operationBasic High Speed Counter Operation Driving high speed counter coilsAvailability of High Speed Counters Input assignmentCounter Speeds Calculating the maximum combined counting speed on FX1S Setting range Device specificationDirection setting Using the SPD instructionRST Device size 11.5 2 Phase Bi-directional Counters C246 to C25011.6 A/B Phase Counters C252 to C255 Example device usage None Data RegistersDevice Mnemonic D General Use Registers Data register updatesData retention Use of diagnostic registers Using the FX2-40AW/APBattery Backed/ Latched Registers Special Diagnostic RegistersWriting to file registers Special caution when using FX1SFile Registers Program memory registersUses Externally Adjusted RegistersUse of Modifiers with Applied Instruction Parameters Index RegistersDevice Mnemonic V,Z Available formsMisuse of the Modifiers Using Multiple Index RegistersModifying a Constant Bit Devices, Individual and Grouped Bits, Words, BCD and HexadecimalAssigning grouped bit devices Moving grouped bit devicesAssigning I/O Interpreting Word Data Word DevicesFX Series Programmable Controllers Word Data Summary Binary Coded Decimal value= ErrorInverted7 Additional1 14.4 Two’s ComplimentSome useful constants Floating Point And Scientific NotationScientific Notation Floating Point Format FLT