05 programming relay bit instructions Training PLC Allen Bradley

DAY SESSION 5-1 LADDER LOGIC PROGRAMMING – BIT INSTRUCTIONS Ladder Logic Programming – Bit Instructions – 10 December 2010 OBJECTIVES After completing this module, you will be able to: • Relay-type Instructions: • Describe the function of the normally open (examine if closed, XIC) instruction • Describe the function of the normally closed (examine if open, XIO) instruction • Explain the function and programming of the coil (output energize, OTE), latch (output latch, OTL) and unlatch (output unlatch, OTU) instructions • Logic-type Instruction: Explain Explain Explain Explain the function of the AND instruction the function of the NOT instruction the function of the OR instruction the function of the Exclusive OR (XOR) instruction 5-2 • • • • Ladder Logic Programming – Bit Instructions – 10 December 2010 I/O IMAGE FILES IN DATA STORAGE The input image file in the processor stores the status of input sensors connected to input module terminals If the Input Sensor Is: Then Its Corresponding Input Image Bit Is: closed (on) on (1) open (off) off (0) The output image file controls the status of actuators wired to output module terminals If the Input Sensor Is: Then Its Corresponding Input Image Bit Is: on (1) open (off) off (0) 5-3 closed (on) Ladder Logic Programming – Bit Instructions – 10 December 2010 RUNG LOGIC • As each conditioning instruction is executed, the addressed bit is examined to see if it matches a certain condition (on or off) • If a complete path of true conditions examined for are found, the rung is set to true 5-4 • The rung must contain a continuous path of true instruction from the start of the rung to the output for the output to be enabled Ladder Logic Programming – Bit Instructions – 10 December 2010 RUNGS Power Rail 0000 0001 0002 5-5 Rung Ladder Logic Programming – Bit Instructions – 10 December 2010 INSTRUCTION Ladder Logic can contain conditional input instruction and output instructions An example of a rung of Ladder Logic is shown in the following graphics Output Instruction ] [ ] [ ] [ ( ) 5-6 Conditional Input Instruction Ladder Logic Programming – Bit Instructions – 10 December 2010 BIT INSTRUCTIONS Use the bit(relay-type) instructions to monitor and control the status of bits ONS XIO XIC Ladder Logic Programming – Bit Instructions OSF OTL OTU OTE 5-7 OSR – 10 December 2010 5-8 BIT INSTRUCTIONS TYPES Ladder Logic Programming – Bit Instructions – 10 December 2010 EXAMINE IF CLOSE (XIC) The XIC instruction examines the data bit to see if it is set data bit = Examine data bit Rung-condition-out is false Data Bit Rung Condition data bit = Rung-condition-out is true 5-9 end Ladder Logic Programming – Bit Instructions – 10 December 2010 EXAMINE IF OPEN (XIO) The XIC: examines the data bit to see if it is cleared data bit = Examine data bit Rung-condition-out is true Data Bit Rung Condition data bit = Rung-condition-out is False 5-10 end Ladder Logic Programming – Bit Instructions – 10 December 2010 OUTPUT ENERGIZE (OTE) When OTE is enabled, controller sets data bit When OTE is disabled, controller clears data bit Rung Condition 5-11 Data Bit Ladder Logic Programming – Bit Instructions – 10 December 2010 OUTPUT LATCH (OTL) When enabled, OTE sets data bit Data bit remains sets until cleared, typically by OTU When disabled, does not change status of data bit Rung Condition 5-12 Data Bit Ladder Logic Programming – Bit Instructions – 10 December 2010 OUTPUT UNLATCH (OTU) When enabled, OTU clears data bit When disabled, does not change status of data bit Rung Rung1 Condition Rung2 Condition Data Bit (light_2) 5-13 Rung Ladder Logic Programming – Bit Instructions – 10 December 2010 ONE SHOT (ONS) When enabled and storage bit is cleared, ONS enables the reminder of the rung When disabled or storage bit is set, ONS disables the reminder of the rung Switch_0 Add Ladder Logic Programming – Bit Instructions Scan – 10 December 2010 5-14 Switch_1 ONE SHOT RISING (OSR) When enabled and storage bit is cleared, OSR sets output bit When enabled and storage bit is set or when disabled, OSR clears output bit Switch_1 Add Ladder Logic Programming – Bit Instructions Scan – 10 December 2010 5-15 Storage Bit ONE SHOT FALLING (OSF) When disabled and the storage bit is set, the OSF instruction sets the output bit When storage bit is cleared, or when enabled, the OSF instruction clears the output bit Switch_0 Add Ladder Logic Programming – Bit Instructions Scan – 10 December 2010 5-16 Storage Bit BOOLEAN LOGIC PROGRAMMING A PLC can nothing without a (ladder logic) program in it The process of converting control objectives into a ladder logic program requires: • details of the process operations • structured thought • solid basic logic understanding • Developed in the 1800’s by James Bool, an Irish mathematician • Can model logical systems with equations which can then be simplified and/or manipulated into new forms • The variable for these equations can ONLY have a value of for false, or for true • Adapt very well to ladder logic programming Ladder Logic Programming – Bit Instructions – 10 December 2010 5-17 Boolean algebra provides the tools needed to analyze and design these systems BOOLEAN EQUATIONS Consist of variables and operations and look very similar to normal algebraic equations Boolean operators: • The four basic operators are: AND OR NOT eXclusive OR (XOR) 5-18 • • • • Ladder Logic Programming – Bit Instructions – 10 December 2010 AND LOGIC One instruction combined in series with another is “AND” SW1 SW2 Normally open, N.O relay contact N.O Boolean equation AND L-1 Battery L-1 = SW1 ● SW2 SW1 SW2 Fig Conventional series circuit SW1 SW2 L-1 N.O N.O Coil 0 0 1 1 The AND’s truth table 5-19 Fig PLC ladder diagram representation of the circuit above L-1 Ladder Logic Programming – Bit Instructions – 10 December 2010 OR LOGIC One instruction combined in parallel with another is “OR” SW1 Boolean equation OR Battery SW2 L-1 L-1 = SW1 + SW2 SW1 SW2 Fig Conventional series circuit SW1 L-1 SW2 L-1 0 1 1 1 The OR’s truth table Ladder Logic Programming – Bit Instructions 5-20 Fig PLC ladder diagram representation of the circuit above – 10 December 2010 NOT LOGIC SW1 L-1 Boolean equation NOT L-1 = SW2 = SW1 Fig N.O instruction SW2 = SW1 L-1 SW1 SW2 = SW1 L-1 1 0 The NOT’s truth table 5-21 Fig Normally closed, N.C, instruction Ladder Logic Programming – Bit Instructions – 10 December 2010 EXCLUSIVE OR LOGIC Boolean equation XOR L-1 = SW1  SW2 L-1 = (SW ● SW2) + (SW1 ● SW2) SW1 SW1 SW2 L-1 SW2 Fig Exclusive OR logic SW1 SW2 L-1 0 0 1 1 1 5-22 The XOR’s truth table Ladder Logic Programming – Bit Instructions – 10 December 2010 NEXT SESSION 5-23 LADDER LOGIC PROGRAMMING – TIMER & COUNTER Ladder Logic Programming – Bit Instructions – 10 December 2010 ... Instructions – 10 December 2010 BIT INSTRUCTIONS Use the bit (relay- type) instructions to monitor and control the status of bits ONS XIO XIC Ladder Logic Programming – Bit Instructions OSF OTL OTU OTE... data bit to see if it is cleared data bit = Examine data bit Rung-condition-out is true Data Bit Rung Condition data bit = Rung-condition-out is False 5-10 end Ladder Logic Programming – Bit Instructions. .. 2010 5-8 BIT INSTRUCTIONS TYPES Ladder Logic Programming – Bit Instructions – 10 December 2010 EXAMINE IF CLOSE (XIC) The XIC instruction examines the data bit to see if it is set data bit = Examine