Data retention, Data register updates | Mitsubishi Electronics FX1S

FX Series Programmable Controllers

Devices in Detail 4

4.12.1General Use Registers

Data registers, as the name suggests, store data. The stored data can be interpreted as a numerical value or as a series of bits, being either ON or OFF.

A single data register contains 16bits or one word. However, two consecutive data registers can be used to form a 32bit device more commonly known as a double word.

If the contents of the data register is being considered numerically then the Most Significant Bit (MSB) is used to indicate if the data has a positive or negative bias. As bit devices can only be ON or OFF, 1 or 0 the MSB convention used is, 0 is equal to a positive number and 1 is equal to a negative number.

		D0
	1
2	0:
	0:
	1:	MSB - Most Significant Bit
	D1	D0
0:
1:	MSB - Most Significant Bit

The diagram above shows both single and double register configurations. In the diagram, at point ➁, it should be noted that the ‘lower’ register D0 no longer has a ‘Most Significant Bit’. This is because it is now being considered as part of a 32bit-double word. The MSB will always be found in the higher 16 bits, i.e. in this case D1. When specifying a 32 bit data register within a program instruction, the lower device is always used e.g. if the above example was to be written as a 32bit instructional operand it would be identified as D0. The second register, D1, would automatically be associated.

Once the data is written to a general data register, it remains unchanged until it is overwritten. When the PLC is turned from RUN to STOP all of the general data registers have their current contents overwritten with a 0 (zero).

Data retention:

•Data can be retained in the general use registers when the PLC is switched from RUN to STOP if special auxiliary relay M8033 is ON.

Data register updates:

•Writing a new data value to a data register will result in the data register being updated with the new data value at the end of the current program scan.

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Mitsubishi Electronics FX1S manual Data retention, Data register updates, General Use Registers

Contents

Programming Manual Page Foreword FX Series Programmable Controllers FX Series Programmable Controllers FAX Back Combined Programming Manual J FX Series Programmable Controllers Software Warnings Hardware 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 Overview Introduction What do You Need to Program a PLC? What is a Programmable Controller? Current Generation CPU all versions Special considerations for programming equipment Manual name Number FX Base Unit Hardware Assocciated Manuals 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 Example How to Read Ladder Logic Load, Load Inverse OUT instructionProgram example Out Timer and Counter Variations Use of dual coils Last coil effectDouble Coil Designation Peripheral limitations And, And Inverse ORI Or, Or Inverse Single Operation flags M2800 to M3071 Load Pulse, Load Trailing Pulse LDF ANF OUT Pulse, And Trailing Pulse ORF ORB Or Pulse, Or Trailing Pulse Or Block Batch processing limitationsSequential processing limitations ANB Block MPS, MRD and MPP usage 13 MPS, MRD and MPP Multiple program examples MCR Master Control and Reset Nested MC program example Resetting timers and counters Set and Reset Timer, Counter Out & Reset Retentive timers16.1Basic Timers, Retentive Timers And Counters Availability of devices Bit countersNormal 32 bit Counters High Speed Counters Leading and Trailing Pulse PLF Usages for INV Inverse No Operation No Operation Program scan 20 End Memo STL Programming FX Series Programmable ControllersSTL Programming General note What is STL, SFC And IEC1131 Part 3? How STL Operates Each step is a programLook Inside an STL Combined SFC Ladder representation How To Start And End An STL ProgramEmbedded STL programs Activating new states Initial Steps Terminating an STL ProgramReturning to Standard Ladder Moving Between STL Steps Using SET to drive an STL coil Using OUT to drive an STL coil OUT is used for loops and jumpsOut is used for distant jumps Basic Notes On The Behavior Of STL programs Rules and Techniques For 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 STL OUT SET Using STL To Select The Most Appropriate Program Limits on the number of branches Using STL To Activate Multiple Flows Simultaneously Limits on the number of branches Instruction Format General Rules For Successful STL Branching General Precautions When Using The FX-PCS/AT-EE Software Simple STL Flow Programming Examples SET STL Identification of normally closed contacts Selective Branch/ First State Merge Example Program Points to note Full STL flow diagram/program Advanced STL Use Devices in Detail FX Series Programmable ControllersDevices in Detail Inputs Configuration detailsAvailable devices Device Mnemonic Outputs Device Mnemonic YAlias O/P Auxiliary Relays Device Mnemonic MGeneral Stable State Auxiliary Relays External loads Battery Backed/ Latched Auxiliary Relays Special Single Operation Pulse Relays Special Diagnostic Auxiliary Relays State Relays Device Mnemonic SGeneral Stable State State Relays PLC FX 1S FX 1N FX 2N Battery Backed/ Latched State Relays Monitoring STL programs Assigned statesSTL/SFC programming IST instruction Annunciator Flags Jumping to the end of the program PointersDevice availability Device Mnemonic P Additional applied instructions Interrupt PointersNested levels Pointer position Timer Interrupts Rules of useInput Interrupts Disabling high speed counter interrupts Driving special auxiliary relaysAdditional notes Disabling Individual Interrupts Constant H Constant KDevice Mnemonic K Example device usage N/A Timers Timer accuracyDevice Mnemonic T General timer operation Selectable TimersDriving special auxiliary coils Retentive Timers Using timers in interrupt or ‘CALL’ subroutines Timers Used in Interrupt and ‘CALL’ Subroutines Internal timer accuracyTimer Accuracy Condition Counters Setting ranges for countersHigh speed counters Device Mnemonic C General/ Latched 16bit UP Counters Battery backed/latched counters Battery backed/ latched counters Selecting the counting directionGeneral/ Latched 32bit Bi-directional Counters Further uses None Basic high speed counter operation Basic High Speed Counter Operation Driving high speed counter coils Input assignment Counter SpeedsAvailability of High Speed Counters Calculating the maximum combined counting speed on FX1S Setting range Device specificationDirection setting Using the SPD instruction RST Device size 11.5 2 Phase Bi-directional Counters C246 to C250 11.6 A/B Phase Counters C252 to C255 Data Registers Device Mnemonic DExample device usage None Data register updates Data retentionGeneral Use Registers Use of diagnostic registers Using the FX2-40AW/APBattery Backed/ Latched Registers Special Diagnostic Registers Writing to file registers Special caution when using FX1SFile Registers Program memory registers Uses Externally Adjusted Registers Use of Modifiers with Applied Instruction Parameters Index RegistersDevice Mnemonic V,Z Available forms Using Multiple Index Registers Modifying a ConstantMisuse of the Modifiers Bit Devices, Individual and Grouped Bits, Words, BCD and Hexadecimal Moving grouped bit devices Assigning I/OAssigning grouped bit devices Interpreting Word Data Word Devices FX Series Programmable Controllers Word Data Summary Binary Coded Decimal value= Error Inverted7 Additional1 14.4 Two’s Compliment Some useful constants Floating Point And Scientific Notation Scientific Notation Floating Point Format FLT