Technical Tip: FortiGateRugged-60F GEN3/GEN5 dual DC input LED behaviour with positive ground power source.

[DPadula]

Description	This article analyses FortiGateRugged-60F GEN3/GEN5 in dual positive ground DC inputs (ex. -48V) but with power sources (ie, RTN on Ve+ is shared between the two sources), when one of the positive ground power sources is OFF or the Ve- cable is disconnected, the DC presence LED may still be turned ON.
Scope	FortiGateRugged-60F GEN3 (P25210-31)/ GEN5 (P25210-50).
Solution	It is recommended to use isolated power sources for power redundancy systems. When a User uses a positive ground source (-48V) a known issue on FortiGateRugged-60F GEN3 units affect the DC presence detection LED behavior. The presence of LED mis-detection behavior does not apply to users using a negative ground source (ex +48V).  The issue has no impact on other areas of the HW functionality and has no impact to any safety and regulatory standard of FGR-60F. The new hardware revision (to be confirmed) has fixed the issue. Below illustrates in negative ground power source, no DC LED issue. This issue only occurs in the case of positive ground sources. The issue does NOT affect customers using negative ground power sources and also does not have any impact on other areas of hardware functionality and no impact on safety and regulatory standards for the FortiGateRugged-60F Gen3/Gen5.