Possible malfunctions

Fault description	Cause	Remedy
A processor module, a communication interface module or an I/O module can not be plugged on the corresponding terminal base or terminal unit.	Terminal bases and terminal units have a mechanical encoding. The encoding makes it impossible to insert a module to the wrong place to prevent dangerous voltages or destroyed modules.	Check the given design scheme of your control cabinet. Get in touch with the planner of the design scheme. Check the ‎⮫ terminal base compatibility and the ‎⮫ terminal unit compatibility.
An AC500-eCo processor module does not start.	Configuration error due to wrong firmware of the option boards.	Update the option boards TA5141-RS232I, TA5142-RS485I and TA5142-RS485 at least to system firmware 3.5.0_HF-7 and boot firmware 3.5.1 or higher. Use Automation Builder 2.5.2 or higher. ⮫ “TA5141-RS232I - Option board for COMx serial communication” ⮫ “TA5142-RS485I - Option board for COMx serial communication” ⮫ “TA5142-RS485 - Option board for COMx serial communication”
The module does not respond and is not available for online connection.	Module is not connected to the power supply. Or module is not functional any more.	Check power supply. Replace the module or HMI. ⮫ “Replace an AC500 module”
I/O module on a hot swap terminal unit does not respond and is not available for online connection.	I/O module is not plugged or damaged.	As soon as the correct and operational I/O module is plugged on the terminal unit, the module is configured and ready to start. ⮫ Hot swap behavior of I/O modules ⮫ Hot swap behavior of remote I/O modules
After hot swap of a (remote) I/O module, the system and/or I/O module does not start.	Wrong I/O module type plugged. The type must be the same as of the replaced module.	Plug the correct I/O module type.
The display of the control panel is black.	Control panel is not connected to the power supply. Or control panel is not functional any more.	Check power supply. Replace the control panel.
ERR LED of the processor module flashes fast. The display shows “AC500”.	A fatal system error occured.	Contact ABB technical support
ERR LED of the processor module flashes. RUN LED is off. The display shows “FAIL”.	Installation or update of firmware, boot project or application failed.	Restart the device. Perform the installation or update again. ⮫ “PLC firmware/application update”
ERR LED is on.	PLC with event + or unacknowledged alarm +.	Use Automation Builder, IEC application or other external access available in your project, e.g., a control panel, to read out and acknowledge the diagnosis messages. In Automation Builder, double-click on a device and select the “Diagnosis” tab to access the diagnosis messages. Or: Read out the diagnosis data on the display of the processor module. ⮫ “Diagnosis messages”
The display of the processor module shows “Demo” for 5 min at every license check. (For processor modules without display only visible when logged in with Automation Builder.)	PLC runs in demo mode because at least one feature license is missing. The demo license is valid for 10 days PLC in run. After this time, PLC will go to stop mode.	You can buy the missing license or extend the demo license via Automation Builder. The PLC will not switch back to run mode until a new license is activated or the licensed features are removed from the PLC application. ⮫ “Managing your licenses” ⮫ “PLC runtime licensing”
Every 10 min, the display of the processor module shows “Grace” for 5 min.	PLC runs in grace mode because at least one feature license which has been available disappeared. If the grace time expires, PLC will go to stop mode.	You need to buy or activate the missing. We recommend to use the Automation Builder for activation. After the PLC is in stop mode, it will not switch back to run mode until a new license is activated or the licensed features are removed from the PLC application. ⮫ “Managing your licenses” ⮫ “PLC runtime licensing”
The CPU displays “noConn” (no connection).	No communication between CPU and display is possible due do very high CPU load (e.g., endless loop in user program and not activated task watchdog).	Check the application for loops and operations they need time. For example file handling. Wait for response from other device who will block the execution from other code.

If a problem persists, ABB technical support must be contacted. To enable efficient support, the affected Automation Builder or Panel Builder project, relevant log files and firmware versions must be provided. Instructions for retrieving log files are described in a corresponding ‎⮫ application note.