Copyright © 2002 Delmar Thomson Learning Chapter 17 Sequencer Instructions

Copyright © 2002 Delmar Thomson Learning Objectives  Describe the function of a sequencer.  Describe the operation of the SLC 500 sequencer output (SQO) instruction.  Explain the function of each SQO status bit.

Copyright © 2002 Delmar Thomson Learning Objectives (cont’d.)  Explain the role of the control (R6) file.  Explain the role of the bit file while programming a sequencer instruction.  Explain what a mask is and why it is used.  Determine the appropriate hexadecimal mask for your application.

Copyright © 2002 Delmar Thomson Learning Sequencer Instructions

Copyright © 2002 Delmar Thomson Learning Sequencer Output Instruction (SQO)  SQO is an output instruction.  Each false to true transition causes the SQO instruction to increment to the next sequence step.  Sequencer steps are stored in a reference data file.

Copyright © 2002 Delmar Thomson Learning SLC 500 PLC Sequencer Output Instruction

Copyright © 2002 Delmar Thomson Learning Bit File Containing Sequencer Step Data

Copyright © 2002 Delmar Thomson Learning Sequencer Operation

Copyright © 2002 Delmar Thomson Learning Sequencer Reference File #B3:0

Copyright © 2002 Delmar Thomson Learning SQO Control File  Sequencer instructions do not have designated data files like timers or counters.  Use R6 control file.  Control file will store sequencer status bits, length, and position data.

Copyright © 2002 Delmar Thomson Learning Three-Word Control Element for the SQO

Copyright © 2002 Delmar Thomson Learning SQO and Associated Status Bits

Copyright © 2002 Delmar Thomson Learning SQO and Hexadecimal Masking  Sequencers use hexadecimal masks similar to the MVM instruction to filter data from the sequencer reference file to the output destination.

Copyright © 2002 Delmar Thomson Learning Only Bits 0 through 7 Will Be Allowed to Pass through the Mask

Copyright © 2002 Delmar Thomson Learning Only Bits Set to a 1 Will Allow Data to Pass

Copyright © 2002 Delmar Thomson Learning Bit Pattern Translated to Hexadecimal

Copyright © 2002 Delmar Thomson Learning Only Bits 8 through 11 Will Be Allowed to Pass through the Mask

Copyright © 2002 Delmar Thomson Learning Selected Single Mask Bits Set to a 1

Copyright © 2002 Delmar Thomson Learning Bit Pattern Translated to Hexadecimal

Copyright © 2002 Delmar Thomson Learning Binary Bit Pattern and Hex Correlations