Allen-Bradley 1756-OB16IS Application Technique
Position-based output control with the maoc instruction
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Also See for 1756-OB16IS:
- Installation instructions manual (10 pages) ,
- User manual (258 pages)
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User Manual, Instruction and Installation Manual
Application Technique
Position-based Output Control with the MAOC Instruction
Catalog Numbers
1756-OB16IS, 1756-OB16IEFS, 1732E-OB8M8SR
Topic
Description
Operation
Configure Output Modules
Configure the Axis
Program the Instruction
This application technique describes applications that use the Motion Arm
Output Cam (MAOC) instruction with and without the use of scheduled
output modules.
Page
2
3
9
11
12
Table of Contents
Related Manuals for Allen-Bradley 1756-OB16IS
Summary of Contents for Allen-Bradley 1756-OB16IS
- Page 1 Application Technique Position-based Output Control with the MAOC Instruction Catalog Numbers 1756-OB16IS, 1756-OB16IEFS, 1732E-OB8M8SR Topic Page Description Operation Configure Output Modules Configure the Axis Program the Instruction This application technique describes applications that use the Motion Arm Output Cam (MAOC) instruction with and without the use of scheduled...
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Page 2: Strobe Trigger
2 Position-based Output Control with the MAOC Instruction Description The MAOC instruction enables you to synchronize digital outputs with axis motion. At low speeds, you can use the instruction with a standard output module to ease the axis and output synchronization. As performance requirements increase, a scheduled output module is necessary to operate with tight time synchronization. -
Page 3: Product Diverting
The instruction can update standard digital output modules at the coarse update rate. However, some high speed applications require a higher degree of accuracy. The 1756-OB16IS, 1756-OB16IEFS, and 1732E-OB8M8SR scheduled output modules improve the accuracy of the MAOC instruction by supporting the ability to schedule output On and Off times. -
Page 4: Factors That Impact Schedule Accuracy
4 Position-based Output Control with the MAOC Instruction Factors that Impact Schedule Accuracy The following sections describe factors that can contribute to a loss of accuracy on the scheduled output modules. Topic Page Minimum Pulse Width Schedule Limitations Position Reference: Actual versus Command Constant versus Changing Velocity Minimum Pulse Width A schedule interval is the course update period (CUP) divided by 16. - Page 5 Current CUP Refer to the table below to determine the minimum pulse width for your application. Table 2 - Minimum Pulse Width Discrete Output MAOC Time Slot (µs) 1756-OB16IS (µs) 1756-OB16IEFS (µs) 1732E-OB8M8SR (µs) CUP (µs) 1000 1500 ≥ 2000...
- Page 6 • H—The schedule turns output 1 Off, but much later than expected. • I—This transition and all of the unmarked transitions are never processed. If the 1756-OB16IS module in this example is replaced with a 1756-OB16IEFS module with a higher schedule count, all of the schedules can be processed and executed.
- Page 7 Position-based Output Control with the MAOC Instruction 7 Position Reference: Actual versus Command The MAOC instruction provides the option to use the actual feedback or the command position as the master reference for the output cam: • For axes configured as Feedback Only, the command position is equal to the actual position.
- Page 8 8 Position-based Output Control with the MAOC Instruction Constant versus Changing Velocity The MAOC instruction calculates schedules without acceleration compensation. Between each CUP, the instruction assumes a linear velocity. However, physical systems behave in a non-linear fashion due to mechanics and physics. This can lead to slight deviations between the scheduled position and physical position of an event.
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Page 9: Configure Output Modules
Using any tag other than the scheduled data tag can cause problems with the execution. • For the 1756-OB16IS, 1756-OB16IEFS, and 1732E-OB8M8SR scheduled output modules, use the default settings shown in the figures below. - Page 10 10 Position-based Output Control with the MAOC Instruction Figure 6 - 1756-OB16IEFS Output Data Figure 7 - 1732E-OB8M8SR Timestamp Rockwell Automation Publication 1756-AT017A-EN-P - January 2013...
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Page 11: Configure The Axis
Position-based Output Control with the MAOC Instruction 11 Configure the Axis The controller uses execution targets to provide a unique identifier for each output cam on an axis. This value enables the controller to reference the MAOC instruction internally. The execution target in the MAOC and MDOC instructions must match to stop the execution of the output cam. -
Page 12: Program The Instruction
12 Position-based Output Control with the MAOC Instruction Figure 10 - AXIS_VIRTUAL This section provides programming examples for three MAOC-based Program the Instruction applications. For detailed information about the MAOC instruction, refer to the online Help within the Studio 5000™ Logix Designer application. Once the MAOC instruction starts, you do not need to terminate the instruction when the axis motion stops. -
Page 13: Strobe Trigger Example
Position-based Output Control with the MAOC Instruction 13 Strobe Trigger Example In this strobe trigger example, a camera takes a picture of labels on boxes as they travel along a conveyor. The conveyor can be driven by any device, such as a servo drive, variable frequency drive, or soft starter. - Page 14 14 Position-based Output Control with the MAOC Instruction Figure 13 shows the configuration of the MAOC instruction for this example. Figure 13 - MAOC Instruction for Strobe Trigger Table 4 - MAOC Operands for Strobe Trigger Operand Configuration Axis Associate the axis with the Conveyor_Feedback tag. Execution Target Specify a value of 0…7.
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Page 15: Applicator Control Example
Position-based Output Control with the MAOC Instruction 15 Table 4 - MAOC Operands for Strobe Trigger (continued) Operand Configuration Axis Arm Position Set to 0.0 with the knowledge that the box is 0.5 m further on the conveyor belt. Cam Arm Position Set to 0.0. - Page 16 16 Position-based Output Control with the MAOC Instruction Figure 15 - Output Cam for Applicator Control Figure 16 shows the configuration of the MAOC Instruction for this example. Figure 16 - MAOC Instruction for Applicator Control Table 5 - MAOC Operands for Applicator Control Operand Configuration Axis...
- Page 17 Position-based Output Control with the MAOC Instruction 17 Table 5 - MAOC Operands for Applicator Control (continued) Operand Configuration Cam End Position Set equal to the unwind distance of the axis. In this example, the distance is 1.0. Output Compensation Specify the tag associated with the output compensation structure, as shown in Figure Execution Mode...
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Page 18: Product Diverting Example
18 Position-based Output Control with the MAOC Instruction Product Diverting Example In this product diverting example, jugs of orange juice pass along the conveyor belt while sensors determine the fullness of each jug. If a jug is not full, it is deflected off of the conveyor belt, as shown below. - Page 19 Position-based Output Control with the MAOC Instruction 19 Figure 19 shows the configuration of the output cam for this example. The configuration schedules the actuator to extend after 9 in. of travel and to stay extended until after an additional inch of travel. Figure 19 - Output Cam for Product Diverting Figure 20 shows the configuration of the MAOC instruction for this example.
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Page 20: Rockwell Automation Support
Your comments will help us serve your documentation needs better. If you have any suggestions on how to improve this document, complete this form, publication RA-DU002, available at http://www.rockwellautomation.com/literature/. Allen-Bradley, ControlLogix, On-Machine, Studio 5000, Rockwell Software, Rockwell Automation, and TechConnect are trademarks of Rockwell Automation, Inc. Trademarks not belonging to Rockwell Automation are property of their respective companies.