The I/O unit and all points are not configured or their configuration does not match the PAC Control strategy; all digital outputs are configured as inputs; all analog points are in their default configuration; PID loops are not configured.
The Control Engine uses an I/O unit's PUC (Power-Up Clear) flag to determine if the unit needs to be configured. The PUC flag is set by the I/O unit when it powers up. If the flag is cleared by anything other than the Control Engine (for instance, by PAC Display), it will not know the I/O unit has powered and needs to be configured.
Opto 22 has resolved this issue.
Both the controller and the I/O unit(s) must have the new firmware. If either the controller or I/O has older firmware, the PUC flag will be used, so I/O will work exactly as it did before this update.
As part of commissioning a project, after the I/O has been configured, use PAC Manager to store each I/O unit’s configuration to flash by selecting, Tools > Inspect, Status Write > Store configuration to flash. By doing so, the I/O configuration resides on the I/O unit and is available should the unit reset or have power cycled to it.