SMC20 with Heidenhain RCN8381 Absolute Rotary Encoder Bit Resolution

I have setup a Heidenhain RCN 8381 Rotary Absolute Single-Turn EnDat2.2 / EnDat02 Encoder with a CU230-2 PN S120 configuration.

Per the "Encoder Configuration for the SIMATIC S7 Technology Functions" manual, I have set p480[E].13 / r487[E].13 to 1 to request the absolute track value cyclically in r483[E] (Enc Gn_XIST2).

https://cache.industry.siemens.com/dl/files/133/109486133/att_1099774/v2/109486133_Geberparametrierung_FAQ_V11_en.pdf

The encoder is specified as a 29 bit encoder and both the incremental Vpp and absolute tracks can be checked with the Heidenhain PWT101 tool showing 29 bit resolution, however I only seem to be getting 17 bit resolution on the absolute track value with the SMC20.

I appear to be able to sample the incremental track up to 29 bits (or even 32 bits) by adjusting the incremental Gn_XIST1 Fine Resolution p418[E] as required, in coordination with the p408[E] pulse/rev value set at 32768.

However, while adjusting the absolute Gn_XIST2 Fine Resolution p419[E], it became apparent only 17 bits (or 16 minus the LSB?) were being transferred, and the fine resolution was just padding with zeroes:

P419=16 - Max Value: 2147467264

01111111111111111100000000000000_2

P419=6 - Max Value: 2097136

00000000000111111111111111110000_2

P419=2 Max Value: 131071

00000000000000011111111111111111_2

I see in a old post (still occasionally referenced on this forum) the higher resolution serial EnDat 2.2 interface is being listed as not functional.

https://support.industry.siemens.com/cs/ww/en/view/22731584

I would think this may be outdated as the purely serial SMC40 exists now.

I've read through the S120 commisioning manual and the previously mentioned encoder setup manual, but it doesn't appear to be specified. The figure 3-178 (and other figures) in the list manual specifies the data flow for the encoder, but doesn't outline the incremental vs absolute track settings.

https://cache.industry.siemens.com/dl/files/911/99682911/att_863921/v1/S120_S150_List_Manual_LH1_0414_eng.pdf

Is Heidenhain doing some sort of interpolation behind the scenes with the absolute and incremental tracks to get the desired 29-bit absolute track resolution on their equipment, something the SMC20 can't?

Is 17 bits the absolute track limit?

Should I be adjusting the coarse resolution values?

Should I be combining absolute and incremental tracks somehow (17bit absolute + 15bit incremental = 32 bits)?

I understand the incremental track should be faster for closed loop control, but the lack of absolute position without manually setting p480[E].13 / r487[E].13 to 1 seems kind of odd.

Several manuals mention the system reads the absolute position only at startup.If the absolute position Gn_XIST2 is supposed to be polled at the beginning of startup and then the incremental value Gn_XIST1 homed based on the absolute value Gn_XIST2, the procedure doesn't seem to work by default with this configuration.Perhaps the error values (which overwrite the absolute position) in r0483[E] are present when the homing/zeroing is supposed to occur and the Gn_XIST1 is not set properly?