Rockwell Automation 1756 ControlLogix, 1756 GuardLogix, 1769 CompactLogix, 1769 Compact GuardLogix, 1789 SoftLogix Programming Manual

Programming Manual

Logix 5000 Controllers Major, Minor, and I/O Faults

1756 ControlLogix, 1756 GuardLogix, 1769 CompactLogix,
1769 Compact GuardLogix, 1789 SoftLogix, 5069
CompactLogix, 5069 Compact GuardLogix, Studio 5000
Logix Emulate
Publication 1756-PM014M-EN-P

Original Instructions

Logix 5000 Controllers Major, Minor, and I/O Faults

personal injury or death, property damage, or economic loss.

Attentions help you identify a hazard, avoid a hazard, and recognize the consequence.

IMPORTANT

Identifies information that is critical for successful application and understanding of the product.

temperatures.

for Personal Protective Equipment (PPE).

Important User Information

Read this document and the documents listed in the additional resources section about installation, configuration, and
operation of this equipment before you install, configure, operate, or maintain this product. Users are required to familiarize
themselves with installation and wiring instructions in addition to requirements of all applicable codes, laws, and standards.

Activities including installation, adjustments, putting into service, use, assembly, disassembly, and maintenance are required to
be carried out by suitably trained personnel in accordance with applicable code of practice.

If this equipment is used in a manner not specified by the manufacturer, the protection provided by the equipment may be
impaired.

In no event will Rockwell Automation, Inc. be responsible or liable for indirect or consequential damages resulting from the use
or application of this equipment.

The examples and diagrams in this manual are included solely for illustrative purposes. Because of the many variables and
requirements associated with any particular installation, Rockwell Automation, Inc. cannot assume responsibility or liability for
actual use based on the examples and diagrams.

No patent liability is assumed by Rockwell Automation, Inc. with respect to use of information, circuits, equipment, or software
described in this manual.

Reproduction of the contents of this manual, in whole or in part, without written permission of Rockwell Automation, Inc., is
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Throughout this manual, when necessary, we use notes to make you aware of safety considerations.

WARNING: Identifies information about practices or circumstances that can cause an explosion in a hazardous environment, which may lead to

ATTENTION: Identifies information about practices or circumstances that can lead to personal injury or death, property damage, or economic loss.

Labels may also be on or inside the equipment to provide specific precautions.

SHOCK HAZARD: Labels may be on or inside the equipment, for example, a drive or motor, to alert people that dangerous voltage may be present.

BURN HAZARD: Labels may be on or inside the equipment, for example, a drive or motor, to alert people that surfaces may reach dangerous

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2 Rockwell Automation Publication 1756-PM014M-EN-P - September 2020

Summary of changes

Topic Name

Reason

This manual includes new and updated information. Use these reference
tables to locate changed information.

Grammatical and editorial style changes are not included in this summary.

Global changes

The Legal noticeshave been updated.

New or enhanced features

This table contains a list of topics changed in this version, the reason for the
change, and a link to the topic that contains the changed information.

Minor Fault Codes on page 33 Updated the Minor Fault Code list to include minor fault type 16,

code 1.

Major fault codes on page 25 Updated the Major Fault Code list to include major fault type 4,

code 95.

Rockwell Automation Publication 1756-PM014M-EN-P - September 2020 3

Summary of changes
Major Faults

Minor Faults

I/O Fault Codes

Index

Table of Contents

Preface

Additional resources ................................................................................... 7

Legal Notices ............................................................................................... 7

Chapter 1

Major Fault State ......................................................................................... 9

Recover from a major fault ................................................................... 9

Important points regarding Add-On Instructions ............................ 10

Fault handling during prescan and postscan .................................... 11

Placement of fault routines ................................................................. 12

Choose where to place the fault routine ............................................. 12

Create a fault routine for a program ......................................................... 13

Change a fault routine assignment of a program ............................. 14

Create a routine for the controller fault handler ..................................... 15

Create a routine for the power-up handler .............................................. 17

Programmatically clearing a major fault .................................................. 19

Create a data type to store fault information ................................... 20

Write a routine to clear the fault ......................................................... 21

Clear a major fault during prescan .......................................................... 22

Test a fault routine .....................................................................................23

Create a user-defined major fault ............................................................ 24

Major fault codes ....................................................................................... 25

Chapter 2

Identify minor faults ................................................................................. 31

Minor fault examples ...........................................................................32

Minor fault codes ........................................................................................ 33

Chapter 3

Indications of I/O faults ............................................................................ 37

I/O Fault Codes ......................................................................................... 38

Rockwell Automation Publication 1756-PM014M-EN-P - September 2020 5

Resource

Description

Manual, publication 1756-RM003

available instruction for a Logix5000 controller.

and other certification details.

Legal Notices

Preface

This manual shows how to monitor and handle major and minor controller
faults. The manual also provides lists of major, minor, and I/O fault codes to
use to troubleshoot the system.

This manual is one of a set of related manuals that show common procedures
for programming and operating Logix 5000 controllers.

Additional resources

For a complete list of common procedures manuals, refer to the

Logix 5000
Controllers Common Procedures Programming Manual, publication 1756­PM001.

The term Logix 5000 controller refers to any controller based on the Logix
5000 operating system.

These documents contain additional information concerning related
products from Rockwell Automation.

Logix5000 Controllers General Instructions Reference

Product Certifications website, http://www.ab.com Provides declarations of conformity, certificates,

Provides programmers with details about each

View or download publications at

http://www.rockwellautomation.com/literature/

. To order paper copies of
technical documentation, contact your local Allen-Bradley distributor or
Rockwell Automation sales representative.

Rockwell Automation publishes legal notices, such as privacy policies, license
agreements, trademark disclosures, and other terms and conditions on the

Legal Notices

page of the Rockwell Automation website.

End User License Agreement (EULA)

You can view the Rockwell Automation End-User License Agreement ("EULA")
by opening the License.rtf file located in your product's install folder on your
hard drive.

Open Source Licenses

The software included in this product contains copyrighted software that is
licensed under one or more open source licenses. Copies of those licenses are
included with the software. Corresponding Source code for open source
packages included in this product are located at their respective web site(s).

Alternately, obtain complete Corresponding Source code by contacting
Rockwell Automation via the Contact form on the Rockwell Automation

Rockwell Automation Publication 1756-PM014M-EN-P - September 2020 7

Preface

website: http://www.rockwellautomation.com/global/about-

us/contact/contact.page

Please include "Open Source" as part of the request text.

A full list of all open source software used in this product and their
corresponding licenses can be found in the OPENSOURCE folder. The default
installed location of these licenses is

Files\Rockwell\Help\FactoryTalk Services Platform\Release

Notes\OPENSOURCE\index.htm

C:\Program Files (x86)\Common

.

8 Rockwell Automation Publication 1756-PM014M-EN-P - September 2020

IMPORTANT

IMPORTANT

Example:

Major Fault State

Chapter 1

Major Faults

This chapter explains major fault codes and how to work with them in the
Logix Designer application.

If a fault condition occurs that prevents an instruction from running, the

instruction aborts and the controller reports a major fault. A major fault halts
logic execution and the controller switches to faulted mode (the OK LED
flashes red).

Depending on the application, you may not want all major faults to shut down
the system. If you do not want all major faults to shut down the system, create
a fault routine to clear the fault and let the application continue to run.

The process of resuming execution after the fault clears is known as fault
recovery.

Do not use fault routines to continually clear all faults on the controller. Program the
fault routine to be selective in the types and number of faults cleared. It is also a
good idea to log the fault occurrence to analyze it later.

When an instruction generates an error due to a fault (for example, a COP with an
indirect addressing programming error), the fault routine skips the instruction and
does not run. This occurs with all instructions.

In a system that uses recipe numbers as indirect addresses, an incorrectly typed number
could produce a major fault.

To keep the entire system from shutting down in the event of this fault, program a fault
routine to clear type 4, code 20, major faults.

See also

Create a routine for the controller fault handler on page 15

Recover from a major fault

Rockwell Automation Publication 1756-PM014M-EN-P - September 2020 9

Clear a major fault during prescan on page 22

These examples show fault routines with logic that take specific action after a

major fault. If the fault clears, the faulted instruction does not run and
execution resumes with the next instruction.

Chapter 1 Major Faults

Important points regarding

Example 1

In this example, a JSR instruction passes an input parameter containing an
indirect address that is out of bounds. If the fault clears, the JSR instruction
aborts (the subroutine does not run) and execution resumes with the EQU
instruction.

Example 2

In this example, the logic inside an Add-On Instruction generates a fault.
While the logic of an Add-On Instruction may look like a subroutine, it is not–
the Add-On Instruction is an instruction. When a fault occurs inside an Add­On Instruction, the remainder of the Add-On Instruction aborts. If the fault
clears, execution resumes with the MOV instruction.

Add-On Instructions

10 Rockwell Automation Publication 1756-PM014M-EN-P - September 2020

Keep these considerations in mind when using Add-On Instructions and

major faults.

• The Add-On Instruction stops running at the instruction that caused
the fault. This means that the remainder of the scan mode routine does
not run.

Fault handling during

Chapter 1 Major Faults

• If the fault clears, execution resumes at the instruction following the
top-level Add-On Instruction invocation. For example, assume the
Add-On Instruction myAoi in Example 2 invokes a nested Add-On
Instruction myNested, which invokes another nested Add-On
Instruction inner. Furthermore, assume that an instruction inside of
inner causes a fault. If the fault clears, execution resumes with the
MOV instruction (the remainder of inner does not execute; the
remainder of myNested does not execute; and the remainder of myAoi
does not execute.)

• During prescan:

• The Logic routine runs (in prescan mode).

• The Prescan routine runs (in normal scan mode).

• During postscan:

• The Logic routine runs (in postscan mode).

• The Postscan routine runs (in normal scan mode).

If a fault occurs while processing the Logic routine, the Add-On Instruction
aborts (the remainder of the Logic routine does not run and the pre-scan and
post-scan routines do not run). If the fault clears, execution resumes at the
instruction following the top-level Add-On Instruction invocation.

prescan and postscan

See also

Create a fault routine for a program on page 13

The behavior of each instruction varies depending on the mode in which it
runs–true, false, prescan, or postscan. For details about what a specific
instruction does in each mode, see the

Instructions Reference Manual, publication number 1756-RM003.

• Prescan provides a system-defined initialization of the user program
when the controller switches from program mode to run mode.

• Postscan provides a system-defined re-initialization of the logic
invoked from an SFC action, when the action shuts down (if SFCs are
configured for Automatic Reset).

If an array index is out of range during prescan, the controller could generate
a major fault. There are a number of ways this could happen: the controller
loses power, encounters a major fault, or the project is saved while online.
Because the user program, during prescan and postscan, cannot assign values
to tags, the only way to correct these issues is to manually initialize the index
variables using the Logix Designer application or to write a fault handler to
ignore the array faults during prescan. To reduce the need for manual
intervention, the Logix Designer application includes an internal fault

Logix 5000 Controllers General

Rockwell Automation Publication 1756-PM014M-EN-P - September 2020 11

Chapter 1 Major Faults

values when an action is shut down.

To clear the fault when

See this section

Condition

Fault Type

Placement of fault routines

Choose where to place the

handler. This handler is only used during prescan and only clears array faults
(type 4, fault codes of 20 of 83).

Tip: Array faults are not ignored during postscan because the user program controls index tag

Use a fault routine to program logic to take specific action after a fault, such
as clearing the fault and continuing to run. Configure fault routines to a

program, controller, or to the Power-Up Handler.

ProgramFaultRoutine

ControllerFaultRoutine

Power-UpFaultHandlerRoutine

See also

Create a fault routine for a program on page 13

Create a routine for the controller fault handler on page 15

Create a routine for the power-up handler on page 17

fault routine

12 Rockwell Automation Publication 1756-PM014M-EN-P - September 2020

Where to place the fault routine depends on the type of fault. Use this table to
determine where in the project to configure the fault routine.

The execution of an instruction faults 4 Creating a Fault Routine for a Program

To clear the fault when

See this section

Condition

Fault Type

A motion axis faults

11

mode

Handler

Create a fault routine for a

Communication with an I/O module fails 3 Creating a Routine for the Controller
Watchdog timer for a task expires 6

Chapter 1 Major Faults

Fault Handler

program

The controller powers up in Run or Remote Run

1 Creating a Routine for the Power-Up

See also

Create a fault routine for a program on page 13

Create a routine for the controller fault handler on page 15

Create a routine for the power-up handler on page 17

Configure any routine as the fault routine for a program. The routine
executes when a program fault occurs before the controller transitions to
fault mode.

To create a fault routine for a program:

1. Open the project in the Logix Designer application.

2. In the Controller Organizer, right-click MainProgram and select
Add>New Routine.

Rockwell Automation Publication 1756-PM014M-EN-P - September 2020 13

3. On the New Routine dialog box, in Name, type the name of the
routine.

Chapter 1 Major Faults

Change a fault routine

4. (optional) In Description, type a description of the routine.

5. In Type, use the default setting, Ladder Diagram.

6. In In Program or Phase, use the default setting, MainProgram.

Tip: If creating a fault routine for the Power-Up Handler or Controller Fault Handler, specify
the program name of either program in In Program or Phase.

7. In Assignment, select Fault.

8. (optional) Select Open Routine to immediately open the ladder logic
program.

9. Select OK.

assignment of a program

See also

Create a routine for the controller fault handler on page 15

Create a routine for the power-up handler on page 17

Choose where to place the fault routine on page 12

Complete these steps to change the routine assigned as the fault routine.

To change a fault routine assignment of a program:

1. In the Controller Organizer, expand the MainTask.

14 Rockwell Automation Publication 1756-PM014M-EN-P - September 2020

IMPORTANT

This occurs with all instructions.

Chapter 1 Major Faults

If there is already a fault routine, it appears in the MainProgram.

2. Right-click MainProgram and select Properties.

3. On the Program Properties - MainProgram dialog box, select the
Configuration tab.

4. In Fault, choose the routine to be the program’s fault routine.

Create a routine for the controller fault handler

5. Select OK.
The program specified in step 4 is now indicated as the fault routine in

the MainProgram.

See also

Create a fault routine for a program on page 13

Use these steps to create a fault routine to operate as the controller fault
handler. Program tags are automatically created during this process.

When programming the fault handler, remember that any instruction that is skipped
as part of the fault-handling program does not run when the main tasks and
associated programs run.

For example, if the fault handler skips a JSR instruction that is causing a major fault,
then that JSR instruction, including all of the programming within the subroutine,
does not run.

When an instruction generates an error due to a fault (for example, a COP with an
indirect addressing programming error), the instruction is skipped and does not run.

Rockwell Automation Publication 1756-PM014M-EN-P - September 2020 15

Chapter 1 Major Faults

To create a routine for the controller fault handler:

1. In the Controller Organizer, right-click Controller Fault Handler and

select New Program.

2. On the New Program dialog box, in Name, type a program name.
Verify that Schedule in is set to Controller Fault Handler.

3. Select OK.

4. In the Controller Organizer, right-click the program created in step 2
and select Add>New Routine.

5. On the New Routine dialog box, in Name, type a name for the routine.

6. In Type, choose the type of routine to create. The default is Ladder
Diagram.

7. In Assignment, use the default setting, Main.

Tip: Even though Fault is an option in the Assignment, assigning the routine as a fault
routine within the Controller Fault Handler is not necessary.

8. Select OK.

16 Rockwell Automation Publication 1756-PM014M-EN-P - September 2020

To

Do this

the controller enters the faulted state.

IMPORTANT

IMPORTANT

Create a routine for the

power-up handler

Chapter 1 Major Faults

The fault routine is created in the Controller Fault Handler program.

9. Double-click the fault routine to edit it.

See also

Recover from a major fault on page 9

Fault handling during prescan and postscan on page 11

The Power-Up Handler is an optional task that executes when the controller
powers up in Run or Remote Run modes.

Prevent the controller from returning to Run or
Remote mode

Direct the controller to take specific actions,
then resume normal operation when power
restored

Do not use fault routines to continually clear all faults on the controller. Program the
fault routine to be selective in the types and number of faults cleared.

When an instruction generates an error due to a fault (for example, a COP with an
indirect addressing programming error), the routine skips the instruction and the
instruction does not run. This occurs with all instructions.

Leave the routine for the Power-Up Handler empty. When
power restored, a major fault (type 1, code 1) occurs and

In the Power-Up Handler fault routine, complete these
steps.

1. Clear the major fault (type 1, code 1).

2. Run the appropriate logic for the specific actions
required.

Rockwell Automation Publication 1756-PM014M-EN-P - September 2020 17