Questions and Answers
The mask parameter is the address of the sequencer file.
False
Due to the way in which a sequencer instruction operates, all output points must be on a single output module.
True
Mechanical sequencer switches are often referred to as drum switches.
True
As a programmed sequencer advances through its steps, binary information is transferred from the sequencer file to the output word.
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When a sequencer operates on an entire output word, all outputs associated with the word are required to be controlled by the sequencer.
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Sequencers are programmed exactly the same for all PLC types.
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The sequencer control parameter is where the status bits, length, and instantaneous position are stored.
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Many sequencer instructions reset the sequencer automatically to step 1 on completion of the last sequence step.
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An event driven sequencer operates in a manner similar to a mechanical drum switch that increments automatically after a preset time period.
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A time-driven sequencer advances to the next step by an external pulsed input.
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The sequencer load instruction shown, _______ data from the source to the sequence file.
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The sequencer shown advances its position whenever:
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The sequencer shown operates whenever:
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The sequencer program shown advances to the next position on each:
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A program modification is to be made to the sequencer shown that requires outputs O:2/12, O:2/13, O:2/14, and O:2/15 to all be energized at step 3. This would require:
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For the sequencer instruction shown, in step 3 ______ will be energized.
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The found bit (FD) of the SQC program shown is set to true whenever the:
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For each bit that the sequencer shown is to control, the corresponding bit of the mask must be set to:
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The sequencer load instruction shown:
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When the SQI instruction is paired with the SQO instruction as illustrated:
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For the Sequencer Output (SQO) instruction shown, the ______ bit is set after the last word in the sequencer file is transferred.
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For the Sequencer Output (SQO) instruction shown, the ______ is the address of the word used to selectively screen out data.
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The sequencer instruction shown controls ____ bits of output word O:2.
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Which of the following would not be classified as a sequencer switch?
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When using a time-driven sequencer, the sequencer advances to the next step:
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When the sequencer instruction shown is at step ____, outputs O:2/2 and O:2/3 will be on and all the rest will be off.
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As the PLC sequencer advances through its steps, information is transferred from:
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Sequencer switches are used whenever a repeatable pattern is required.
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The sequencer input instruction shown is true whenever the unmasked input data are _____ the data stored in the sequencer file.
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Study Notes
Sequencer Instructions Overview
- The mask parameter identifies the address of the sequencer file; it is important for controlling output.
- All output points of a sequencer instruction need to be on a single output module for effective operation.
- Mechanical sequencer switches are commonly known as drum switches.
- When advancing through steps, programmed sequencers transfer binary information from the sequencer file to the output word.
Operation and Functionality
- Outputs controlled by the sequencer do not necessarily require all signals associated with the output word to be used.
- Each PLC type requires unique programming for sequencers; there is no universal approach.
- The sequencer control parameter stores essential information, including status bits, sequence length, and current position.
- Many sequencers automatically reset to step 1 after completing the last step in the sequence.
Types of Sequencers
- Event-driven sequencers operate differently from mechanical drum switches; they do not automatically increment after a preset time.
- Time-driven sequencers do not advance to the next step based solely on external pulsed inputs; they operate on preset conditions.
Instruction Details
- The sequencer load instruction is responsible for copying data from the source to the sequencer file.
- Various conditions, such as false-to-true transitions on specific signals (S1, S2), can prompt the sequencer to advance its position.
- For the sequencer to function correctly, a timer must reach its preset value to trigger operations.
Output Control
- The programmed sequencer allows energization of specific outputs when it reaches a designated step.
- Found bits (FD) in the sequencer program are activated when the source pattern matches the sequencer file word.
- To control bits within the sequencer, corresponding bits in the mask must be set to 1.
Instruction Pairing and Operation
- SQI and SQO instructions must be paired correctly to function; they allow synchronized input and output sequences.
- The sequencer output instruction (SQO) sets a Done (DN) bit after transferring the last word from the sequencer file.
- Sequencer control can selectively screen out data using a mask, which specifies the address for this purpose.
Application of Sequencers
- A sequencer can control up to six bits of the output word, demonstrating its capability in managing complex outputs.
- Sequencer switches are ideal for applications requiring repeatable patterns, ensuring consistency in operation.
- Sequencer instructions match unmasked input data against the data stored in the sequencer file, determining true states accordingly.
Miscellaneous
- Pressure switches are not categorized as sequencer switches, highlighting the specificity of sequencer technology applications.
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Description
Test your knowledge on sequencer instructions with this set of flashcards. Learn key concepts such as the mask parameter, output point requirements, and types of switches used. Perfect for anyone studying automation and control systems.
