Sony STR-DA7ES Serial Feedback for Volume

I’ve been a Roomie Remote user from the beginning. I just bought a new piece of gear, and I am revisiting the custom code sets I created years ago using codes from the DDK. All of my devices have been successfully controlled serially via GC-100(s) for years now. However, I have 1 command that I just cannot figure out. How do I receive serial feedback for the volume?

Here is a link to manual that I used to create the code set

Data Format (Host Controller <-> Amplifier)

STX+BC+PDC+CMD + Data1±----+DataN+CS

The terminological definition is as follows.

STX 02 H : Start of text code

BC : Byte Count (Number of bytes of until before CS from PDC.)

PDC : Product Code

CMD : Command (Opecode)

DataN : DataBlock(0<M+FAH)

CS : Check Sum. A value from which 8 bits of low ranks of the sum from BC to CS are set to 0.

OK, so here are my codes


STX 02 H : 0x02

BC : 0x04

PDC : 0x0a (AMP)

CMD : 0x92 (VolumeStatusReq)

DataN : 0x00 (ZONE=main room)

DataN : 0x00 (VOL ATTRIBUTE=current)

CS : 0xc9

Pretty straight forward. Next,


STX 02 H : 0x02

BC : 0x06

PDC : 0x0a (AMP)

CMD : 0x52 (VolumeSet)

DataN : 0x00 (ZONE =main room)

DataN : 0x01 (VOL ATTRIBUTE=current direct value setting)

DataN : 0xa6 (VOL Step_High= volume_upper_data) (set to -90 in this example)

DataN :0x00 (VOL Step_Low= volume_lowerer_data)

CS : 0x61

This one is particularly perplexing because of the parameter in the 3rd data block. How do you calculate a checksum when one of the values is unknown? Lastly,


8 (Sony Binary Volume Format) per the DDK

Any help is greatly appreciated.