How STL Operates, Look Inside an STL | Mitsubishi Electronics FX1S

FX Series Programmable Controllers

STL Programming 3

3.2How STL Operates

As previously mentioned, STL is a system which allows the user to write a program which functions in much the same way as a flow chart, this can be seen in the diagram opposite.

STL derives its strength by organizing a larger program into smaller more manageable parts. Each of these parts can be referred to as either a state or a step. To help identify the states, each is given a unique identification number. These numbers are taken from the state relay devices (see page 4-6 for more details).

M8002

S 0

X0

X1

S 22

T0

S 27

T7

X0

X1

S 26

X15

3.2.1Each step is a program

Each state is completely isolated from all other states within the whole program. A good way to envisage this, is that each state is a separate program and the user puts each of those programs together in the order that they require to perform their task. Immediately this means that states can be reused many times and in different orders. This saves on programming time AND cuts down on the number of programming errors encountered.

A Look Inside an STL

On initial inspection the STL program looks as if it is a rather basic flow diagram. But to find out what is really happening the STL state needs to be put ‘under a microscope’ so to speak. When a single state is examined in more detail, the sub-program can be viewed.

With the exception of the STL instruction, it will be immediately seen that the STL sub-program looks just like ordinary programming.

The STL instruction is shown as a ‘fat’ normally open contact.

All programming after an STL instruction is only active when the associated state coil is active.

The transition condition is also written using standard programming.

This idea re-enforces the concept that STL is really a method of sequencing a series of events or as mentioned earlier ‘of joining lots of smaller programs together’.

		2
		S 22
		T0
		1
	STL	2
	STL	Y22
	S 22	Y22
	S 22	K20
		T0
		T0
		SET S 27
		1

3-2

Image 54

Mitsubishi Electronics FX1S manual How STL Operates, Each step is a program, Look Inside an STL

Contents

Programming Manual Page FX Series Programmable Controllers Foreword FX Series Programmable Controllers FAX Back Combined Programming Manual J FX Series Programmable Controllers Hardware Warnings Software Warnings FX 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 Overview What is a Programmable Controller? What do You Need to Program a PLC? Special considerations for programming equipment Current Generation CPU all versions Assocciated Manuals Manual name Number FX Base Unit Hardware Manual 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 Example Load, Load Inverse OUT instructionProgram example Timer and Counter Variations Out Use of dual coils Last coil effectDouble Coil Designation And, And Inverse Peripheral limitations Or, Or Inverse ORI Load Pulse, Load Trailing Pulse Single Operation flags M2800 to M3071 Pulse, And Trailing Pulse LDF ANF OUT Or Pulse, Or Trailing Pulse ORF ORB Or Block Batch processing limitationsSequential processing limitations Block ANB 13 MPS, MRD and MPP MPS, MRD and MPP usage Multiple program examples Master Control and Reset MCR Nested MC program example Set and Reset Resetting timers and counters Timer, Counter Out & Reset Retentive timers16.1Basic Timers, Retentive Timers And Counters Normal 32 bit Counters Bit countersAvailability of devices High Speed Counters PLF Leading and Trailing Pulse Inverse Usages for INV No Operation No Operation 20 End Program scan Memo STL Programming FX Series Programmable ControllersSTL Programming What is STL, SFC And IEC1131 Part 3? General note How STL Operates Each step is a programLook Inside an STL Embedded STL programs How To Start And End An STL ProgramCombined SFC Ladder representation Activating new states Initial Steps Terminating an STL ProgramReturning to Standard Ladder Using SET to drive an STL coil Moving Between STL Steps Using 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 programs T001 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 SET Using STL To Activate Multiple Flows Simultaneously Limits on the number of branches Limits on the number of branches General Rules For Successful STL Branching Instruction Format General Precautions When Using The FX-PCS/AT-EE Software Programming Examples Simple STL Flow Identification of normally closed contacts SET STL Points to note Selective Branch/ First State Merge Example Program Full STL flow diagram/program Advanced STL Use Devices in Detail FX Series Programmable ControllersDevices in Detail Available devices Configuration detailsInputs Device Mnemonic Outputs Device Mnemonic YAlias O/P Auxiliary Relays Device Mnemonic MGeneral Stable State Auxiliary Relays Battery Backed/ Latched Auxiliary Relays External loads Special Diagnostic Auxiliary Relays Special Single Operation Pulse Relays State Relays Device Mnemonic SGeneral Stable State State Relays Battery Backed/ Latched State Relays PLC FX 1S FX 1N FX 2N STL/SFC programming Assigned statesMonitoring STL programs IST instruction Annunciator Flags Device availability PointersJumping to the end of the program Device Mnemonic P Nested levels Interrupt PointersAdditional applied instructions Pointer position Timer Interrupts Rules of useInput Interrupts Additional notes Driving special auxiliary relaysDisabling high speed counter interrupts Disabling Individual Interrupts Device Mnemonic K Constant KConstant H Example device usage N/A Timers Timer accuracyDevice Mnemonic T General timer operation Selectable TimersDriving special auxiliary coils Using timers in interrupt or ‘CALL’ subroutines Retentive Timers Timer Accuracy Internal timer accuracyTimers Used in Interrupt and ‘CALL’ Subroutines Condition High speed counters Setting ranges for countersCounters Device Mnemonic C Battery backed/latched counters General/ Latched 16bit UP Counters Battery backed/ latched counters Selecting the counting directionGeneral/ Latched 32bit Bi-directional Counters Basic high speed counter operation Further uses None Driving high speed counter coils Basic High Speed Counter Operation Input assignment Counter SpeedsAvailability of High Speed Counters Calculating the maximum combined counting speed on FX1S Direction setting Device specificationSetting range Using the SPD instruction RST 11.5 2 Phase Bi-directional Counters C246 to C250 Device size 11.6 A/B Phase Counters C252 to C255 Data Registers Device Mnemonic DExample device usage None Data register updates Data retentionGeneral Use Registers Battery Backed/ Latched Registers Using the FX2-40AW/APUse of diagnostic registers Special Diagnostic Registers File Registers Special caution when using FX1SWriting to file registers Program memory registers Externally Adjusted Registers Uses Device Mnemonic V,Z Index RegistersUse of Modifiers with Applied Instruction Parameters Available forms Using Multiple Index Registers Modifying a ConstantMisuse of the Modifiers Bits, Words, BCD and Hexadecimal Bit Devices, Individual and Grouped Moving grouped bit devices Assigning I/OAssigning grouped bit devices Word Devices Interpreting Word Data FX Series Programmable Controllers Binary Coded Decimal value= Error Word Data Summary 14.4 Two’s Compliment Inverted7 Additional1 Floating Point And Scientific Notation Some useful constants Scientific Notation Floating Point Format FLT