Mitsubishi Electronics FX1S manual Internal timer accuracy, Timer Accuracy, Condition

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FX Series Programmable Controllers

Devices in Detail 4

4.9.4Timers Used in Interrupt and ‘CALL’ Subroutines

FX1S

FX1N

FX2N

FX2NC

If timers T192 to T199 and T246 to T249 are used in a CALL subroutine or an interruption routine, the timing action is updated at the point when an END instruction is executed. The output contact is activated when a coil instruction or an END instruction is processed once the timers current value has reached the preset (maximum duration) value.

Timers other than those specified above cannot function correctly within the specified circumstances.

When an interrupt timer (1 msec resolution) is used in an interrupt routine or within a ‘CALL’ subroutine, the output contact is activated when the first coil instruction of that timer is executed after the timer has reached its preset (maximum duration) value.

4.9.5Timer Accuracy

Timer accuracy can be affected by the program configuration. That is to say, if a timer contact is used before its associated coil, then the timer accuracy is reduced.

The following formulas give maximum and minimum errors for certain situations. However, an average expected error would be approximately;

1.5 × The program scan time

Condition 1:

The timer contact appears after the timer coil.

X10

T0

T0

Maximum timing error:

2 × Scan time + The input filter time

Minimum timing error:

Input filter time - The timer resolution

Condition 2:
The timer contact appears before the timer coil.	T0
The timer contact appears before the timer coil.

X10

Maximum timing error:

3 × Scan time + The input filter time

Minimum timing error:

Input filter time- The timer resolution

Y10

Y10

T0

Internal timer accuracy:

• The actual accuracy of the timing elements within the PLC hardware is;

±10 pulses per million pulses. This means that if a 100 msec timer is used to time a sin- gle day, at the end of that day the timer will be within 0.8 seconds of the true 24 hours or 86,400 seconds. The timer would have processed approximately 864,000; 100 msec pulses.

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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 Detailed device information What is a Program?Outline of Basic Devices Used in Programming How to Read Ladder Logic ExampleProgram example Load, Load InverseOUT instruction Timer and Counter Variations OutDouble Coil Designation Use of dual coilsLast coil effect 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 ORBSequential processing limitations Or BlockBatch 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 counters16.1Basic Timers, Retentive Timers And Counters Timer, Counter Out & ResetRetentive timers 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 noteLook Inside an STL How STL OperatesEach step is a program How To Start And End An STL Program Combined SFC Ladder representationEmbedded STL programs Activating new statesReturning to Standard Ladder Initial StepsTerminating an STL Program Using SET to drive an STL coil Moving Between STL StepsOut is used for distant jumps Using OUT to drive an STL coilOUT is used for loops and jumps Rules and Techniques For STL programs Basic Notes On The Behavior Of 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 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 MnemonicAlias O/P OutputsDevice Mnemonic Y General Stable State Auxiliary Relays Auxiliary RelaysDevice Mnemonic M Battery Backed/ Latched Auxiliary Relays External loadsSpecial Diagnostic Auxiliary Relays Special Single Operation Pulse RelaysGeneral Stable State State Relays State RelaysDevice Mnemonic S 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 positionInput Interrupts Timer InterruptsRules of use Driving special auxiliary relays Disabling high speed counter interruptsAdditional notes Disabling Individual InterruptsConstant K Constant HDevice Mnemonic K Example device usage N/ADevice Mnemonic T TimersTimer accuracy Driving special auxiliary coils General timer operationSelectable Timers 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 CountersGeneral/ Latched 32bit Bi-directional Counters Battery backed/ latched countersSelecting the counting direction Basic high speed counter operation Further uses NoneDriving high speed counter coils Basic High Speed Counter OperationAvailability of High Speed Counters Input assignmentCounter Speeds 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 Example device usage None Data RegistersDevice Mnemonic D General Use Registers Data register updatesData retention 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 formsMisuse of the Modifiers Using Multiple Index RegistersModifying a Constant Bits, Words, BCD and Hexadecimal Bit Devices, Individual and GroupedAssigning grouped bit devices Moving grouped bit devicesAssigning I/O 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