I Have a PLC (Tri-PLC T100MD888) that will be managing a Tri-Fuel standby generator. Normal power for the PLC will be a 120 VAC to 12VDC linear power supply. The 120 VAC will either be power company or from the generator. There is a delay between switch overs of up to a minute or more. The generator power supply is a 12VDC lead acid battery that will be charged and maintained by the generator's charging system and a 120 VAC charger. The issue is, the brief period while the generator comes up to speed, or switching back to power company power, the PLC needs to remain up and running, otherwise when it would reset, the generator would stop, and oscillation between power sources would result. Have thought about parallel diodes, but the lead acid battery and charges could frequently have voltage above the 12VDC linear power supply. How can I keep the PLC from resetting?