Time sync between PC and PLC via SNTP
Which node do you need as a time server - I suppose PC in your case?
Time synchronization is always working with UTC. So you wrore "plc is sync with the PC" - what does it mean? Perhaps the PLC received the PC's time, but as UTC.
I don't know if AC500 supports Local Time function (AC800M has that option). May be not?
But it depends why do you need the local time in the PLC. You can send the UTC time to different words (or INT) by Hour, Minute and Sec, and then to mofify these words as you need (ADD or SUB with your local time difference)