What does halt code 8A57 mean in %SW125 of a Unity/Control Expert controller?

FA198664

27/07/2020

Issue
A Unity Pro or Control Expert PLC went into halt and System Word 125 = 16#8A57 (35415 Dec)

Product line
Unity Pro, Control Expert, Modicon M340, Unity Momentum, Modicon Quantum, Modicon Premium

Resolution
The error code: % SW125 = 16#8A57 (E_ERR_NULL_INPUT_SCALE) indicates an identical high and low limit problem on blocks using scaling. 

For example, the Scaling Block or any blocks related to the regulations with high and low limits. (PI_B, PIDFF, AUTOTUNE, etc).
This error sets the PLC to HALT. Review and monitor the code to determine how this condition is occurring. 

The error could be detected when the online modification validation is performed. Performing an Analyze project could find the cause of the error.

The Diagnostic viewer should take you to the problem spot if you select the message and right click then select 'initialize editor'