Mitsubishi Electronics FX1S manual T001 K20 K50

Page 60

FX Series Programmable Controllers

STL Programming 3

•When an STL step transfers control to the next STL step there is a period (one scan) while both steps are active. This can cause problems with dual coils; particularly timers.

If timers are dual coiled care must be taken to ensure that the timer operation is completed during the active STL step.

If the same timer is used in consecutive steps then it is possible that the timer coil is never deactivated and the contacts of the timer will not be reset leading to incorrect timer operation.

The example opposite identifies an unacceptable use of timer T001. When control passes from S30 to S31 T001 is not reset because its coil is still ON in the new step.

S 30

T001

S 31

S 32

K20

T001

T001

K50

T001

Note: As a step towards ensuring the correct operation of the dual timers they should not be used in consecutive STL steps.

Following this simple rule will ensure each timer will be reset correctly before its next operation.

•As already mentioned, during the transfer between steps, the current and the selected steps will be simultaneously active for one program scan. This could be thought of as a hand over or handshaking period.

This means that if a user has two outputs contained in consecutive steps which must NOT be active simultaneously they must be interlocked. A good example of this would be the drive signals to select a motors rotation direction. In the example Y11 and Y10 are shown interlocked with each other.

S30

S 31

Y10

Y11

Y11 Y10

3-8

Image 60

Contents Programming Manual Page FX Series Programmable Controllers ForewordFX Series Programmable Controllers FAX Back Combined Programming Manual J FX Series Programmable Controllers Hardware Warnings Software 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 Introduction OverviewWhat is a Programmable Controller? What do You Need to Program a PLC?Special considerations for programming equipment Current Generation CPU all versionsAssocciated Manuals Manual name Number FX Base Unit HardwareManual name Number FX DU, GOT and DM units Memo Basic Program Instructions FX Series Programmable ControllersBasic Program Instructions What is a Program? Outline of Basic Devices Used in ProgrammingDetailed device information How to Read Ladder Logic ExampleLoad, Load Inverse OUT instructionProgram example Timer and Counter Variations OutUse of dual coils Last coil effectDouble Coil Designation And, And Inverse Peripheral limitationsOr, Or Inverse ORILoad Pulse, Load Trailing Pulse Single Operation flags M2800 to M3071Pulse, And Trailing Pulse LDF ANF OUTOr Pulse, Or Trailing Pulse ORF ORBOr Block Batch processing limitationsSequential processing limitations Block ANB13 MPS, MRD and MPP MPS, MRD and MPP usageMultiple program examples Master Control and Reset MCRNested MC program example Set and Reset Resetting timers and countersTimer, Counter Out & Reset Retentive timers16.1Basic Timers, Retentive Timers And Counters Bit counters Availability of devicesNormal 32 bit Counters High Speed CountersPLF Leading and Trailing PulseInverse Usages for INVNo Operation No Operation20 End Program scanMemo STL Programming FX Series Programmable ControllersSTL Programming What is STL, SFC And IEC1131 Part 3? General noteHow STL Operates Each step is a programLook Inside an STL How To Start And End An STL Program Combined SFC Ladder representationEmbedded STL programs Activating new statesInitial Steps Terminating an STL ProgramReturning to Standard Ladder Using SET to drive an STL coil Moving Between STL StepsUsing OUT to drive an STL coil OUT is used for loops and jumpsOut is used for distant jumps Rules and Techniques For STL programs Basic Notes On The Behavior Of STL programsT001 K20 K50 Single Signal Step Control Method 1 Using locking devicesMethod 2 Special Single Pulse Flags Restrictions Of Some Instructions When Used With STL Using ‘jump’ operations with STLRestrictions on using applied instructions Using STL To Select The Most Appropriate Program STL OUT SETUsing STL To Activate Multiple Flows Simultaneously Limits on the number of branchesLimits on the number of branches General Rules For Successful STL Branching Instruction FormatGeneral Precautions When Using The FX-PCS/AT-EE Software Programming Examples Simple STL FlowIdentification of normally closed contacts SET STLPoints to note Selective Branch/ First State Merge Example ProgramFull STL flow diagram/program Advanced STL Use Devices in Detail FX Series Programmable ControllersDevices in Detail Configuration details InputsAvailable devices Device MnemonicOutputs Device Mnemonic YAlias O/P Auxiliary Relays Device Mnemonic MGeneral Stable State Auxiliary Relays Battery Backed/ Latched Auxiliary Relays External loadsSpecial Diagnostic Auxiliary Relays Special Single Operation Pulse RelaysState Relays Device Mnemonic SGeneral Stable State State Relays Battery Backed/ Latched State Relays PLC FX 1S FX 1N FX 2NAssigned states Monitoring STL programsSTL/SFC programming IST instructionAnnunciator Flags Pointers Jumping to the end of the programDevice availability Device Mnemonic PInterrupt Pointers Additional applied instructionsNested levels Pointer positionTimer Interrupts Rules of useInput Interrupts Driving special auxiliary relays Disabling high speed counter interruptsAdditional notes Disabling Individual InterruptsConstant K Constant HDevice Mnemonic K Example device usage N/ATimers Timer accuracyDevice Mnemonic T General timer operation Selectable TimersDriving special auxiliary coils Using timers in interrupt or ‘CALL’ subroutines Retentive TimersInternal timer accuracy Timers Used in Interrupt and ‘CALL’ SubroutinesTimer Accuracy ConditionSetting ranges for counters CountersHigh speed counters Device Mnemonic CBattery backed/latched counters General/ Latched 16bit UP CountersBattery backed/ latched counters Selecting the counting directionGeneral/ Latched 32bit Bi-directional Counters Basic high speed counter operation Further uses NoneDriving high speed counter coils Basic High Speed Counter OperationInput assignment Counter SpeedsAvailability of High Speed Counters Calculating the maximum combined counting speed on FX1S Device specification Setting rangeDirection setting Using the SPD instructionRST 11.5 2 Phase Bi-directional Counters C246 to C250 Device size11.6 A/B Phase Counters C252 to C255 Data Registers Device Mnemonic DExample device usage None Data register updates Data retentionGeneral Use Registers Using the FX2-40AW/AP Use of diagnostic registersBattery Backed/ Latched Registers Special Diagnostic RegistersSpecial caution when using FX1S Writing to file registersFile Registers Program memory registersExternally Adjusted Registers UsesIndex Registers Use of Modifiers with Applied Instruction ParametersDevice Mnemonic V,Z Available formsUsing Multiple Index Registers Modifying a ConstantMisuse of the Modifiers Bits, Words, BCD and Hexadecimal Bit Devices, Individual and GroupedMoving grouped bit devices Assigning I/OAssigning grouped bit devices Word Devices Interpreting Word DataFX Series Programmable Controllers Binary Coded Decimal value= Error Word Data Summary14.4 Two’s Compliment Inverted7 Additional1Floating Point And Scientific Notation Some useful constantsScientific Notation Floating Point Format FLT