On the GTN ARINC 429 IN diagnostics page, I’m getting:
- Label field. 121, 104, 320, 314, 000, 117, etc
- SSM field. 00 or 11
- Data field. 1’s and 0’s
- SDI field. Always 00

When GTN is displaying the test screen right after boot-up, the glide path indicator doesn’t get displayed on the EFIS.