Allen-Bradley MicroLogix 1400 Programmable Controllers

An invalid output has been specified for a PTOX instruction. Only Output 2, Output 3, and Output 4 are valid choices. This is a configuration error that causes the controller to fault, and the User Fault Routine does not execute.

An output overlap is detected, meaning multiple functions are assigned to the same physical output. This is a configuration error (e.g., PTO0 and PTO1 attempting to use a single output) that causes the controller to fault, and the User Fault Routine does not execute.

This error occurs when Acceleration Count and Deceleration parameters are not defined during the transition to Run mode, specifically when the Accel/Decel Pulses Independent (ADI) bit is set (1) in the PTOX configuration. This is a configuration error preventing proper motion control.

No error is present in the Pulse Train Output (PTOX) subsystem. The system is operating normally without any detected faults or warnings.

The default program has been loaded into the controller's memory. This typically happens if power was lost during a program download or transfer from a memory module, or if a RAM integrity test failed. This indicates a potential issue with the controller's non-volatile memory or its power supply.

The controller experienced an unexpected reset, possibly due to electrical noise in the environment or an internal hardware malfunction. Consequently, the default program has been loaded, indicating a loss of the previously loaded user program.

An error occurred with the memory module's internal memory, indicating that the user program stored on it is corrupt. This fault can also manifest when attempting to switch the controller to Run mode. The integrity of the stored program is compromised.

The controller detected corruption in its ROM or RAM while powered up, or a background integrity check failed. This indicates a critical issue with the controller's internal memory, potentially affecting program execution and data storage.

A hardware fault has occurred within the memory module itself, or the installed memory module is not compatible with the controller's current operating system (OS). This prevents proper operation or program loading.

A failure occurred during the transfer of data or a program to or from the memory module. This indicates an issue with the transfer process, which might be intermittent or due to a faulty module.

An unexpected and critical software error has occurred within the controller's operating system or runtime environment. This typically halts controller operation and may require reinitialization of data.

An unexpected and critical hardware error has occurred within the controller itself. This type of fault typically indicates a severe malfunction in the controller's physical components, preventing normal operation.

Status bit S:2/9 is set in the controller, indicating that the user program stored in the non-volatile RAM (NVRAM) or memory module does not match the user program currently loaded and executing in the controller. This is a nonrecoverable fault.

The user program stored in the memory module is incompatible with the controller's current Operating System (OS). This is a non-user fault, indicating a fundamental mismatch that prevents the program from executing correctly.

At power-up, the user program loaded into the controller is found to be incompatible with its Operating System (OS). This is a non-user fault preventing the controller from starting correctly, similar to a memory module incompatibility but occurring during initial program load.

A minor fault bit (any of bits 0-7) in status file S:5 was set at the end of a program scan. This is a recoverable fault, indicating a minor issue that doesn't halt the controller immediately but should be addressed to prevent potential operational problems.

The program scan time exceeded the configured watchdog timeout value, which is stored in status file S:3H. This is a nonrecoverable fault, indicating that the controller's program took too long to execute, potentially due to an infinite loop, excessive processing, or an incorrectly set watchdog timer.

An error occurred in the Selectable Timed Interrupt (STI) configuration. This is a recoverable fault, meaning the controller can potentially continue operation if the error is addressed, but the STI function may not work as intended.

A fault routine number was entered in status file S:29, but either the fault routine was not physically created in the program, or the entered file number was less than 3 or greater than 255. This is a non-user fault, preventing proper fault handling.

An indirect address reference in the ladder program attempts to access memory locations outside of the entire data file space. This is a recoverable fault, indicating a programming error that could lead to unexpected behavior, data corruption, or controller instability.

DNP3 10K events are enabled simultaneously with Recipe/Data Log functionality in the user program. This is a non-user fault, indicating an unsupported configuration combination within the controller's firmware that prevents both features from operating concurrently.

The DNP3 event configuration (specifically status bit S:36/11 for 10K events) in the latest user project downloaded differs from the configuration present in the controller at power-up. This is a non-user fault requiring a power cycle for the new settings to take effect.

An error occurred in the External Interrupt Input (EII) configuration. This is a recoverable fault, meaning the controller can potentially continue operation if the error is addressed, but the EII function may not work as intended.

The nesting level of JSR (Jump to Subroutine) instructions exceeded the controller's available memory space for the call stack. This is a non-user fault, indicating an architectural limitation has been surpassed by an overly deep program structure.

The program contains an instruction that the controller's current firmware does not support. This is a non-user fault, indicating a compatibility issue between the program and the controller's instruction set, often due to programming for a different model or version.

A sequencer instruction (SQO - Sequencer Output, SQC - Sequencer Compare, or SQL - Sequencer Load) has a length or position parameter that attempts to reference memory locations outside of the entire data file space. This is a recoverable fault, indicating an out-of-bounds memory access error in the program.

The length or position parameter of a Bit Shift Left (BSL), Bit Shift Right (BSR), Find First Last (FFL), Find First Unset (FFU), Look For Last (LFL), or Look For Unset (LFU) instruction references memory locations outside of the entire data file space. This is a recoverable fault, indicating an out-of-bounds memory access error.

A negative value was loaded into either the preset or accumulator word of a timer instruction. This is a recoverable fault, as timer values (presets and accumulators) are typically non-negative and negative values are not logically valid for timing functions.

The program contains a Temporary End (TND), Refresh (REF), or Service Communication instruction within an interrupt subroutine (STI, EII, HSC) or a user fault routine. These specific instructions are not permitted in interrupt contexts due to their system-level implications or timing characteristics. This is a nonrecoverable fault.

This error is generated whenever a hard stop condition is detected by the PTOX subsystem, indicating that a physical limit or emergency stop input has been activated. This error does not fault the controller.

The configured PTOX output (2, 3, or 4) is in a forced condition, meaning its state is overridden by user software or another program. The forced condition must be removed for the PTOX to operate. This error does not fault the controller and clears automatically when the force is removed.

The operating frequency value (OFS) specified for the PTOX instruction is less than 0 or greater than 100,000 pulses per second. This error faults the controller and indicates an invalid frequency parameter. It can be cleared by logic within the User Fault Routine.

The accelerate/decelerate parameters (ADP) are either less than zero, greater than half the total output pulses to be generated (TOP), or exceed a specific documented limit (see page 103). This error faults the controller and indicates an invalid motion parameter. It can be cleared by logic within the User Fault Routine.

The PTOX is in the idle state, and two or more of the following bits are simultaneously set: Enable (EN) bit, Jog Pulse (JP) bit, and Jog Continuous (JC) bit. This indicates conflicting jog commands. This error does not fault the controller and automatically clears when the error condition is removed.

The jog frequency (JF) value specified for the PTOX instruction is less than 0 or greater than 100,000 pulses per second. This error faults the controller and indicates an invalid frequency parameter for jog operations. It can be cleared by logic within the User Fault Routine.

The total output pulses to be generated (TOP) for the PTOX instruction are less than zero. This error faults the controller and indicates an invalid motion parameter, as pulse counts must be non-negative. It can be cleared by logic within the User Fault Routine.

The Modbus TCP server received a packet that it could not identify or parse. This indicates a received packet that does not correspond to any known Modbus TCP frame type or supported protocol, often due to incorrect protocol or malformation.

This error is for firmware internal use only, indicating a failure to allocate a buffer. This suggests a memory exhaustion issue within the controller for Modbus TCP operations, preventing the processing of new data.

An established Modbus TCP connection was unexpectedly terminated. This indicates a loss of communication between the client and server without a graceful shutdown, often due to network issues or the remote peer failing.

An incoming Modbus TCP connection attempt was rejected because its source IP address did not pass the controller's configured IP address validation rules. This is a security feature to control access.

A received Modbus TCP packet's header had an invalid format. This indicates the packet structure does not conform to the Modbus TCP specification, likely due to a misconfigured or faulty sending device.

A received Modbus TCP packet's header contained an invalid Cyclic Redundancy Check (CRC). This indicates data corruption during transmission or an improperly formed packet originating from the sender.

A received Modbus TCP packet contained an invalid Cyclic Redundancy Check (CRC) in its data portion. This indicates data corruption during transmission or an improperly formed packet from the sender.

This error is for firmware internal use only, indicating a failure to allocate a packet. This suggests a memory issue within the controller for Modbus TCP packet handling, preventing new packets from being processed or transmitted.

A received Modbus TCP packet was explicitly rejected by the controller. This might be due to security policies, internal resource limitations, or unsupported operations within the Modbus TCP server implementation, even if the packet format is valid.

This error is for firmware internal use only, indicating a failure to release a packet. This suggests an internal memory management issue where packet buffers are not being properly deallocated, potentially leading to memory leaks or resource exhaustion.

This error is for firmware internal use only, indicating an internal queue is full. This suggests an overload condition within the controller's Modbus TCP processing, where incoming requests are exceeding the system's ability to process them.

An error occurred during the socket accept operation. This prevents the Modbus TCP server from accepting incoming client connection requests after a successful listen, often due to system resource limitations or internal network stack issues.

An error occurred during the socket bind operation. This prevents the Modbus TCP server from associating a local IP address and port with the socket, indicating a problem with the configured network interface or port availability.

An error occurred during the socket connect operation. This prevents the Modbus TCP client from establishing a connection to a remote Modbus TCP server, often due to network connectivity problems or incorrect destination settings.

An error occurred during the socket creation operation. This prevents the Modbus TCP client/server from establishing communication sessions, typically due to system resource limitations or network stack issues.

An error occurred during the socket delete operation. This indicates a failure to deallocate or destroy a socket resource, potentially leading to resource leaks or exhaustion over time.

An error occurred during the socket disconnect operation. This indicates a failure to properly terminate an established Modbus TCP connection, potentially leaving orphaned connections or preventing new ones.

An error occurred during the socket listen operation. This prevents the Modbus TCP server from listening for incoming client connections on the designated port, often indicating a port conflict or permission issue.

An error occurred during the socket receive operation. This indicates a failure to receive data over an established Modbus TCP connection, often due to a broken connection or the remote peer not sending data.

An error occurred during the socket send operation. This indicates a failure to transmit data over an established Modbus TCP connection, often due to a broken connection or issues with the remote peer.

An error occurred during the socket unaccept operation. This indicates a failure to properly stop accepting new client connections, potentially leaving the server in an inconsistent state.

An error occurred during the socket unbind operation. This indicates a failure to release the local IP address and port associated with a socket, potentially leaving resources held or in an unstable state.

An error occurred during the socket unlisten operation. This indicates a failure to properly stop listening for incoming connections, which could leave resources held or in an unstable state.

No error is currently detected in the Modbus TCP Server or Client operations. The system is functioning normally.