Page 291 - Programmable Logic Controllers, Fifth Edition - Mobile version

Bit Shift Left BSL EN • Each of the remaining 3 zones is equipped with a
reject pilot light to warn the assembler to ignore the
Array ? DN product if the lamp is on.
Control ?
Source Bit ? • Each successive product activating the Product_
Length ? Sensor will advance the data bit one position to the
Figure 12-31 ControlLogix Bit Shift Left (BSL) instruction. left in the register, energizing the 3 remaining reject
lamps in turn.
• The MOV instruction of rung 2 posts the BSL_
• If the product is deemed defective the inspector Array contents to the four Zone_Outputs.
actuates the Reject_Button energizing the Reject_ • Activating the Reset_Button of rung 3 at any time
Source_Bit through its seal circuit. energizes both rung MOV instructions to reset the
• The rejected product passes by the Productor_ BSL_Array and Control_Status to 0.
Sensor and as a result the Reject_Source_Bit (1) is
loaded into the first step of the BSL_Array which
energizes the Z1 reject pilot light. 12.5 Word Shift Operations
• At the same time the Control_Status.DN bit mo- The first in, first out (FIFO) instructions are word shift
mentarily changes state to open the seal-in circuit operations that are similar to bit shift operations. Word
to the Reject_Source_Bit, readying it for the next shifting provides a simpler method of loading and un-
product reject. loading data into a file, usually called the stack. It is often

Ladder logic program
Reject_Button
Inputs <Local:1:I.Data.1> Control_Status.DN Reject_Source_Bit Outputs
L1 0 L2
Reject_Source_Bit <Local:2:O.Data.0> Z1
Reject_Button
Product_Sensor <Local:2:O.Data.1> Z2
<Local:1:I.Data.0> BSL
1 Bit Shift Left EN
Array BSL_Array DN <Local:2:O.Data.2> Z3
Product_Sensor Control Control_Status
Source Bit Reject_Source_Bit
Length 4
<Local:2:O.Data.2> Z4
MOV
2 Move
Source BSL_Array
0
Reset_Button Dest Zone_Outputs
0
Reset_Button
<Local:1:I.Data.2>
3 Move MOV Move MOV
Source 0 Source 0
Dest BSL_Array Dest Control_Status.POS
0 0

Reject_Source_Bit Reject_Button Tag Name Value Style Data Type
+ BSL_Array 0 Decimal DINT
+ Control_Status {. . . } CONTROL
– Zone_Outputs 0 Decimal DINT
BSL_Array Zone_Outputs.0 0 Decimal BOOL
Unload_Bit Zone_Outputs.1 0 Decimal BOOL
Zone_Outputs.2 0 Decimal BOOL
Zone_Outputs.3 0 Decimal BOOL
Product_Sensor 0 Decimal BOOL
Reject_Button 0 Decimal BOOL
Reject_Source_Bit 0 Decimal BOOL
Reset_Button 0 Decimal BOOL

Figure 12-32 ControlLogix pass/fail inspection program.
Source: Photo courtesy Omron Industrial Automation, www.ia.omron.com.

272 Chapter 12 Sequencer and Shift Register Instructions

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