In the last rows of api_test.lua there are two methods that use the function gma.canbus.hardkey(code, press, hold). This function emulates actions on physical keys on the console.

It is advisable to “unpress” the button after every stroke, i.e.:

gma.canbus.hardkey(54, true, false)
gma.canbus.hardkey(54, false, false)

eventually adding a gma.sleep() with a short delay between.

The key codes discovered so far are listed below, one remains unknown.

   1:
   2:
   3: Ch Pg +
   4: Ch Pg -
   5: Fd Pg +
   6: Fd Pg -
   7: Bt Pg +
   8: Bt Pg -
   9: Pause [large]
  10: Go - [large]
  11: Go + [large]
  12: X1
  13: X2
  14: X3
  15: X4
  16: X5
  17: X6
  18: X7
  19: X8
  20: X9
  21: X10
  22: X11
  23: X12
  24: X13
  25: X14
  26: X15
  27: X16
  28: X17
  29: X18
  30: X19
  31: X20
  32: List
  33: User 1
  34: User 2
  35:
  36: U1
  37: U2
  38: U3
  39: U4
  40: ⦿ ("Nipple")
  41: Fix
  42: Select
  43: Off
  44: Temp
  45: Top
  46: On
  47: <<<
  48: Learn
  49: >>>
  50: Go - [small]
  51: Pause [small]
  52: Go + [small]
  53: Oops
  54: Esc
  55: Edit
  56: Goto
  57: Update
  58: Time
  59: Store
  60: Blind
  61: Freeze
  62: Prvw [Preview]
  63: Assign
  64: Align
  65: B.O. [Blackout]
  66: View
  67: Effect
  68: MA
  69: Delete [Delete]
  70: Page
  71: Macro
  72: Preset
  73: Copy
  74: Sequ [Sequence]
  75: Cue
  76: Exec [Executor]
  77:
  78:
  79:
  80:
  81:
  82: Channel
  83: Fixture
  84: Group
  85: Move
  86: 0 [Numeric]
  87: 1 [Numeric]
  88: 2 [Numeric]
  89: 3 [Numeric]
  90: 4 [Numeric]
  91: 5 [Numeric]
  92: 6 [Numeric]
  93: 7 [Numeric]
  94: 8 [Numeric]
  95: 9 [Numeric]
  96: + [Plus]
  97: - [Minus]
  98: . [Dot]
  99: Full
 100: Highlt [Highlight]
 101: Solo
 102: Thru
 103: If
 104: At
 105: Clear
 106: Please
 107: Up
 108: Set
 109: Prev [Previous]
 110: Next
 111: Down
 112:
 113:
 114:
 115:
 116: Help
 117: Backup
 118: Setup
 119: Tools
 120: V1
 121: V2
 122: V3
 123: V4
 124: V5
 125: V6
 126: V7
 127: V8
 128: V9
 129: V10
 130:
 131:
 132:
 133:
 134:
 135:
 136:
 137:
 138:
 139:
 140:
 141:
 142:
 143:
 144:
 145:
 146:
 147:
 148:
 149:
 150:
 151:
 152:
 153:
 154:
≥155: Pause [large]

The only undiscovered key is Backg [Background]. Since the Backg key has no function (yet), we might only guess it among the unassigned keycodes, probably it corresponds to 35.