# DiGiCo S31 (S-Series) — Studio Mon control + iPad relay

This connection does two things:

1. **Controls which channels feed one buss** — by default the *Studio* buss — plus any aux send
   level/on/pan, channel mute/fader, buss master fader/mute and snapshot recall, with feedbacks,
   variables and ready-made presets.
2. **Relays the DiGiCo iPad app.** An S-Series console talks to exactly one iPad at a time.
   Companion takes that slot; the iPad apps point at the Companion computer instead of the
   console. Everything an app sends is forwarded to the console unchanged and every console
   message is copied to every app seen recently, so several iPads can be used at once.

## What the console speaks (verified on "S31 AB", 2026-10-15)

The S31's **iPad** extension speaks the DiGiCo Pad / SD-style OSC tree over UDP:

| Address | Reply | Notes |
| --- | --- | --- |
| `/Console/Name/?` | `/Console/Name "S31 AB"` | used as keepalive |
| `/Console/Input_Channels/?`, `/Console/Aux_Outputs/?` | int counts (60, 25) | 25 busses, each in aux *or* group mode |
| `/Console/Aux_Outputs/modes/?` | 25 ints, 2 = stereo, 1 = mono | |
| `/Input_Channels/N/Channel_Input/name/?` | string | |
| `/Input_Channels/N/fader/?`, `/mute/?` | float dB (−150 = −∞), float 0/1 | |
| `/Input_Channels/N/Aux_Send/M/send_level` | float dB, −150 = off | write a float |
| `/Input_Channels/N/Aux_Send/M/send_on` | float 0/1 | write int 0/1 |
| `/Input_Channels/N/Aux_Send/M/send_pan` | float 0..1, 0.5 centre | |
| `/Input_Channels/N/Group_Send/M/group` | float 0/1 | group assign; write int 0/1 |
| `/Aux_Outputs/M/Buss_Trim/name/?`, `/Group_Outputs/M/Buss_Trim/name/?` | string | a buss is named on one side only |
| `/Aux_Outputs/M/fader`, `/mute` (and `/Group_Outputs/M/…`) | float | buss masters |
| `/Snapshots/Current_Snapshot/?`, `/Snapshots/names/?` | int; `/Snapshots/name [i, cue×100, 0, name]` | |

A query is the address plus `/?` with no argument; the reply is the same address without `/?`.
Every reply goes to the controller IP and **Send Port** configured on the console, never to the
asking socket, which is why a fixed local port is bound. The lowercase S-Series *OSC Control*
command list (`/channel/N/…`, `/console/resend`) is **not** answered on the iPad leg; it belongs
to the separate *OSC Control* extension and is available here as an alternative command set.

## Console setup (once, at the surface)

Main Menu → **Extensions → iPad**:

| Console field | Value |
| --- | --- |
| iPad IP address | the Companion computer (AB-ProPresenter: `10.3.11.152`) |
| Send port *(console → iPad)* | this connection's **Local receive port** (default `9000`) |
| Receive port *(iPad → console)* | this connection's **Console receive port** (default `8000`) |
| iPad connection enabled | yes |

## iPad app setup

In the DiGiCo S app connect page, for every iPad:

| iPad field | Value |
| --- | --- |
| Console IP | the Companion computer, **not** the console |
| Send port | this connection's **Relay port** (default `8000`) |
| Receive port | this connection's **iPad receive port** (default `9000`) |

An iPad that goes quiet for *Forget an iPad after* seconds is dropped from the fan-out list.
`$(S31:relay_clients)` shows how many are live.

## Studio Mon buss

Set **Studio Mon buss number** (1-25, the console's buss order). The module reads the buss
names and works out whether it is an **aux** (send level + on/off per channel) or a **group**
(assign on/off per channel); override with *Studio Mon buss type* if needed. On this console:

| Buss | Aux name | Group name |
| --- | --- | --- |
| 1-8 | VOCAL VERB, VOCAL SLAP, TRACKS, CLK-GD-MD, VOCAL DELAY, VOCALS, TB, MC/SpkrBcastOut | |
| 9-13 | | BAND, VOCALS, MISC, DRUMS, DRUM CRUSH |
| 14-17 | DRUM PLATE, AG VERB, FOH Spkr, Studio TB | |
| 18 | | Broadcast mix |
| 19-21 | FX, Prop & Spot, Drum Room Verb | |
| 23-25 | | CAFE, **Studio**, Master |

The default is buss **24 "Studio"** (stereo group). Presets under *Studio Mon* give one
on/off button per input (green when assigned/on, label = channel name); for an aux buss the
+1 dB / −1 dB nudge presets appear as well.

## Variables

`$(S31:ch_N_name)`, `$(S31:aux_N_name)`, `$(S31:group_N_name)`, `$(S31:buss_N_mode)`,
`$(S31:mon_N_on)`, `$(S31:mon_N_level)`, `$(S31:mon_name)`, `$(S31:mon_mode)`,
`$(S31:snapshot_name)`, `$(S31:connected)`, `$(S31:relay_clients)`, `$(S31:last_send_touched)`,
`$(S31:last_rx)`.

## Troubleshooting

- **No reply from console**: the console only sends to the iPad IP + Send Port set on the
  console. Check those, and that nothing else on this computer owns the local receive port
  (on AB-ProPresenter UDP 8002 belongs to Dante Via; 8000 and 9000 are free).
- **Learn mode** logs every new address pattern once (Connections → log). Touch a control on
  the surface and the matching address appears; `$(S31:last_send_touched)` shows the last
  send/assign that changed.
- Press **Reload from console** after a session change to refresh names and levels.