There is a difference between serial and ARINC.
The original poster asked about a 530W hooked to a D120, which is only done via serial. There is no time in the serial string that the 530 puts out.
The aviation format that the 430, 530, 480, 300XL, and other panel mounted devices use does not have time in it. There's nothing we can do about this. Hooking up only via serial means we can't set the time.
If you have an HS34 on a D100, D10A, or D180, or an SV-ARINC-429 with a SkyView, then we can set the time via that ARINC connection.