For plc errors and solutions, you can find the error reasons from the table below and try the solutions found in return. You can find the error description in the table.
Major Faults
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.
Major fault codes
Code | Cause | Recovery Method |
| 1-1 | The controller powered on in Run mode. | Execute the power up handler. |
1-16 | I/O communication configuration fault detected. (CompactLogix 1768-L4x controllers only.) | Reconfigure the number of communication modules on the 1768 bus side of the controller: • 1768-L43 has a maximum of two modules. • 1768-L45 has a maximum of four modules. • Up to four Sercos modules • Up to two NetLinx communication modules |
1-40 | If the controller uses a battery, then the battery does not contain enough charge to save the user program on power down. If the controller uses an ESM (Energy Storage Module), then the ESM does not contain enough charge to save the user program on power down | • For controllers that use a battery, replace the battery. • For controllers that use an ESM (Energy Storage Module): • Allow the ESM to fully charge before powering down the controller. • Replace the ESM if the ESM is removable, or replace the controller if the ESM is not removable. • If the problem persists, contact Rockwell Automation support. |
1-60 | For a controller with no memory card installed, the controller: • Detected a non-recoverable fault. • Cleared the project from memory | 1. Clear the fault. 2. Download the project. 3. Change to Remote Run or Run mode. If the fault persists: 1. Before cycling power to the controller, record the state of the OK and RS232 status indicators. 2. Contact Rockwell Automation support. |
1-61 | For a controller with a memory card installed, the controller: • Detected a non-recoverable fault. • Wrote diagnostic information to the memory card. • Cleared the project from memory. | 1. Clear the fault. 2. Download the project. 3. Change to Remote Run/Run mode. If the fault persists, contact Rockwell Automation support. |
1-62 | For a controller with a Secure Digital (SD) card installed, the controller: • Detected a nonrecoverable fault. • Wrote diagnostic information to the memory card. When in this state, the controller will not open any connections or allow a transition to Run mode. | 1. Clear the fault. 2. Download the project. 3. Change to Remote Run or Run mode. If the fault persists, contact Rockwell Automation support. |
3-16 | A required I/O module connection failed | Check: • The I/O module is in the chassis. • The electronic keying requirements. • The Controller Properties Major Faults tab and the Module Properties Connection tab for more information about the fault |
3-20/21 | Possible problem with the chassis. | Not recoverable – replace the chassis |
3-23 | At least one required connection was not established before going into Run mode. | Wait for the controller I/O light to turn green before changing to Run mode |
4-16 | Unknown instruction encountered | Remove the unknown instruction. This probably happened due to a program conversion process |
4-20 | Array subscript too big, control structure .POS or .LEN is invalid | Adjust the value to be within the defined range. Don’t exceed the array size or go beyond dimensions defined. |
4-21 | Control structure .LEN or .POS < 0. | Adjust the value so that it is > 0 |
4-31 | The parameters of the JSR instruction do not match those of the associated SBR or RET instruction. | Pass the appropriate number of parameters. If too many parameters are passed, the extra ones are ignored without any error |
4-34 | A timer instruction has a negative preset or accumulated value. | Fix the program to not load a negative value into timer preset or accumulated. |
4-42 | JMP to a label that did not exist or was deleted. | Correct the JMP target or add the missing label. |
4-82 | A sequential function chart (SFC) called a subroutine and the subroutine tried to jump back to the callingSFC. Occurs when the SFC uses either a JSR or FOR instruction to call the subroutine. | Remove the jump back to the calling SFC. |
4-83 | The data tested was not inside the required limits. This occurs with array subscripts used with Boolean arrays and bit level addressing. | Adjust the value to be within the valid range. Do not exceed the array size or go beyond the dimensions defined. |
4-84 | Stack overflow. | Reduce the subroutine nesting levels or the number of parameters passed. |
4-89 | In an SFR instruction, the target routine does not contain the target step. | Correct the SFR target or add the missing step |
4-90 | Using a safety instruction outside a safety task. | Place the safety instruction inside the safety task. |
4-91 | Equipment Phase instruction is being called from outside an Equipment Phase program. | Only use the instruction in an Equipment Phase program. |
4-94 | Nesting limits exceeded | Restructure the project to reduce the subroutine nesting levels |
4-990-999 | User-defined major fault. |
