Saving a PLC program to flash in a Quantum PLC using either Modbus, MB+ or Ethernet TCP/IP causes the NOE to reboot

Issue
Saving a PLC program to flash in a Quantum PLC using either Modbus, Modbus Plus or Ethernet TCP/IP causes the NOE to reboot.

Product Line
140NOE77101 version 4.8, 140NOE77111 version 4.8

Environment
ProWORX 32, Concept

Resolution
When a 'ProWORX 32' or 'Concept' PLC program is saved to flash using TCP/IP through a '140NOE771xx' module, TCP/IP communications to the NOE can be lost for up to ten minutes. As a result of this, it is highly recommended that the PLC and the connected TCP/IP devices (i.e., SCADA, HMI, etc.) are not in operational mode when a 'Save to Flash' is performed.
During the 'Save to Flash' function, The legacy 984 executive firmware in the cpu is designed to stop communicating to the IO modules configured in the application. When this happens, all IO modules in the rack will go into fallback mode. If there are any NOE modules in the application, they will stop communicating to the external devices (i.e., HMI.SCADA, etc.). If the PLC application is large, it may also take a period of time to perform the 'Save to Flash'.

When the NOE backplane communications to the cpu is stopped, the NOE is designed to reboot itself. When the NOE reboots, it must re-establish all the communications links again. Depending on the number of links that need to get re-established, it can take two (2) to ten (10) minutes for the NOE to finish rebooting. During the reboot of the NOE, the PLC programming software (i.e., 'ProWORX 32', 'Concept') will also get disconnected. After the NOE finishes rebooting, it will automaticaly get reconnected the PLC programming software.

Using a VPN connection to perform a 'Save to Flash' is not recommended because it might prevent the automatic reconnection of the NOE to the PLC programming software. If the re-connection is prevented by the VPN, the user will not be able to restart the PLC.

If the user does not want the behavior of the NOE rebooting during a 'Save to Flash' function, they will need to upgrade the exec firmware of the 'Quantum cpu ('140 534 14x' or '140CPU434 14x') to Unity and aslo upgrade the PLC program to Unity. (The Unity exec firmware is designed to maintain the CPU connection to the IO modules during a 'Save to Flash' of a Unity application.)