Shure DFR22 Control Spec

Summary

Shure DFR22 is a digital feedback reduction processor. Control via RS-232 serial at 19200 8N1. Protocol uses D0h prefix and D1h suffix. Commands cover preset recall, input/output channel levels, and matrix mixer routing.

Transport

protocols:
  - serial
serial:
  baud_rate: 19200
  data_bits: 8
  parity: none
  stop_bits: 1
  flow_control: none
auth:
  type: none  # inferred: no auth procedure in source

Traits

# From command examples:
# - powerable: UNRESOLVED - no power on/off commands in source
# - queryable: yes (QRY command, query forms for most subcommands)
# - routable: yes (MIX connection commands route input to output)
# - levelable: yes (L subcommand with 0-127 range)
traits:
  - queryable
  - routable
  - levelable

Actions

# QRY - query all parameters
- id: query_all
  label: Query All Parameters
  kind: action
  params: []
  description: Returns state of all parameters as if each queried individually. Format: D0h DFR22 <unit> QRY D1h

# PRE - preset control
- id: preset_set
  label: Set Preset
  kind: action
  params:
    - name: preset
      type: integer
      description: Three-digit preset number (e.g., 001)
  description: Sets current preset. Format: D0h DFR22 <unit> PRE <3-digit preset> D1h

- id: preset_query
  label: Query Preset
  kind: action
  params: []
  description: Queries current preset. Format: D0h DFR22 <unit> PRE D1h

# INP - input channel control
- id: input_level_set
  label: Set Input Level
  kind: action
  params:
    - name: channel
      type: enum
      values: [001, 002, ALL]
    - name: value
      type: integer
      description: Gain value 0-127 (0 = -Infinity, 1-26 = -105 to -42.5dB in 2.5dB steps, 27-127 = -40 to +10dB in 0.5dB steps)
  description: Sets input channel gain level. Format: D0h DFR22 <unit> INP <channel> L 00<byte> D1h

- id: input_level_inc
  label: Increment Input Level
  kind: action
  params:
    - name: channel
      type: enum
      values: [001, 002]
    - name: value
      type: integer
      description: Increment amount (0-127)
  description: Increases input gain by supplied value. Format: D0h DFR22 <unit> INP <channel> I <3-digit value> D1h

- id: input_level_dec
  label: Decrement Input Level
  kind: action
  params:
    - name: channel
      type: enum
      values: [001, 002]
    - name: value
      type: integer
      description: Decrement amount (0-127)
  description: Decreases input gain by supplied value. Format: D0h DFR22 <unit> INP <channel> D <3-digit value> D1h

- id: input_mute
  label: Set Input Mute
  kind: action
  params:
    - name: channel
      type: enum
      values: [001, 002, ALL]
    - name: value
      type: enum
      values: [000, 001, 002]
      description: "000 = mute off, 001 = mute on, 002 = toggle"
  description: Sets input mute state. Format: D0h DFR22 <unit> INP <channel> M <3-digit value> D1h

- id: input_sensitivity
  label: Set Input Sensitivity
  kind: action
  params:
    - name: channel
      type: enum
      values: [001, 002]
    - name: value
      type: enum
      values: [000, 001, 002]
      description: "000 = +4 dBu, 001 = -10 dBV, 002 = toggle"
  description: Sets input sensitivity. Format: D0h DFR22 <unit> INP <channel> S <3-digit value> D1h

- id: input_polarity
  label: Set Input Polarity
  kind: action
  params:
    - name: channel
      type: enum
      values: [001, 002]
    - name: value
      type: enum
      values: [000, 001, 002]
      description: "000 = positive, 001 = negative, 002 = toggle"
  description: Sets input polarity. Format: D0h DFR22 <unit> INP <channel> P <3-digit value> D1h

- id: input_mute_query
  label: Query Input Mute
  kind: action
  params:
    - name: channel
      type: enum
      values: [001, 002]
  description: Queries mute status. Format: D0h DFR22 <unit> INP <channel> M D1h

- id: input_sensitivity_query
  label: Query Input Sensitivity
  kind: action
  params:
    - name: channel
      type: enum
      values: [001, 002]
  description: Queries sensitivity. Format: D0h DFR22 <unit> INP <channel> S D1h

- id: input_polarity_query
  label: Query Input Polarity
  kind: action
  params:
    - name: channel
      type: enum
      values: [001, 002]
  description: Queries polarity. Format: D0h DFR22 <unit> INP <channel> P D1h

# OUT - output channel control
- id: output_level_set
  label: Set Output Level
  kind: action
  params:
    - name: channel
      type: enum
      values: [001, 002, ALL]
    - name: value
      type: integer
      description: Gain value 0-127
  description: Sets output channel gain level. Format: D0h DFR22 <unit> OUT <channel> L 00<byte> D1h

- id: output_level_inc
  label: Increment Output Level
  kind: action
  params:
    - name: channel
      type: enum
      values: [001, 002]
    - name: value
      type: integer
      description: Increment amount
  description: Increases output gain. Format: D0h DFR22 <unit> OUT <channel> I <3-digit value> D1h

- id: output_level_dec
  label: Decrement Output Level
  kind: action
  params:
    - name: channel
      type: enum
      values: [001, 002]
    - name: value
      type: integer
      description: Decrement amount
  description: Decreases output gain. Format: D0h DFR22 <unit> OUT <channel> D <3-digit value> D1h

- id: output_mute
  label: Set Output Mute
  kind: action
  params:
    - name: channel
      type: enum
      values: [001, 002, ALL]
    - name: value
      type: enum
      values: [000, 001, 002]
  description: Sets output mute state. Format: D0h DFR22 <unit> OUT <channel> M <3-digit value> D1h

- id: output_clip
  label: Set Output Clip/Pad
  kind: action
  params:
    - name: channel
      type: enum
      values: [001, 002]
    - name: value
      type: enum
      values: [000, 001, 002]
      description: "000 = no pad, 001 = 18dB pad, 002 = 12dB pad"
  description: Sets output clipping pad (OUTPUT ONLY). Format: D0h DFR22 <unit> OUT <channel> C <3-digit value> D1h

- id: output_mute_query
  label: Query Output Mute
  kind: action
  params:
    - name: channel
      type: enum
      values: [001, 002]
  description: Queries output mute state.

- id: output_clip_query
  label: Query Output Clip/Pad
  kind: action
  params:
    - name: channel
      type: enum
      values: [001, 002]
  description: Queries output clip/pad state.

# MIX - matrix mixer control
- id: mix_level_set
  label: Set Mix Level
  kind: action
  params:
    - name: mixer
      type: enum
      values: [001, 002]
      description: Mixer number (output strip)
    - name: channel
      type: enum
      values: [001, 002, OUT]
      description: Channel (input strip); OUT for output fader
    - name: value
      type: integer
      description: Gain value 0-127
  description: Sets mix point gain level. Format: D0h DFR22 <unit> MIX <mixer><channel> L <3-digit value> D1h

- id: mix_level_inc
  label: Increment Mix Level
  kind: action
  params:
    - name: mixer
      type: enum
      values: [001, 002]
    - name: channel
      type: enum
      values: [001, 002]
    - name: value
      type: integer
  description: Increases mix point gain.

- id: mix_level_dec
  label: Decrement Mix Level
  kind: action
  params:
    - name: mixer
      type: enum
      values: [001, 002]
    - name: channel
      type: enum
      values: [001, 002]
    - name: value
      type: integer
  description: Decreases mix point gain.

- id: mix_mute
  label: Set Mix Mute
  kind: action
  params:
    - name: mixer
      type: enum
      values: [001, 002]
    - name: channel
      type: enum
      values: [001, 002, OUT]
    - name: value
      type: enum
      values: [000, 001, 002]
  description: Sets mix point mute state.

- id: mix_polarity
  label: Set Mix Polarity
  kind: action
  params:
    - name: mixer
      type: enum
      values: [001, 002]
    - name: channel
      type: enum
      values: [001, 002, OUT]
    - name: value
      type: enum
      values: [000, 001, 002]
  description: Sets mix point polarity.

- id: mix_connect
  label: Connect Mix Route
  kind: action
  params:
    - name: mixer
      type: enum
      values: [001, 002]
      description: Mixer number (output strip)
    - name: channel
      type: enum
      values: [001, 002]
      description: Input channel to route (cannot be OUT)
    - name: value
      type: enum
      values: [000, 001]
      description: "000 = disconnect, 001 = connect"
  description: Routes input channel to output mixer. Format: D0h DFR22 <unit> MIX <mixer><channel> C <3-digit value> D1h

- id: mix_connect_query
  label: Query Mix Connection
  kind: action
  params:
    - name: mixer
      type: enum
      values: [001, 002]
    - name: channel
      type: enum
      values: [001, 002]
  description: Queries mix routing state.

Feedbacks

# Device echoes command strings back as acknowledgement.
# Query commands return parameter values.
# Multiple responses when "ALL" used - one per channel.
# UNRESOLVED: exact response string format for each query type not fully detailed in source.
- id: command_echo
  type: string
  description: Device echoes the command string back as acknowledgement

- id: preset_response
  type: string
  description: Response to preset query - returns current preset number

- id: level_response
  type: integer
  description: Response to level query - returns current gain value 0-127

- id: mute_response
  type: enum
  values: [000, 001, 002]
  description: "000 = mute off, 001 = mute on, 002 = toggle state"

- id: sensitivity_response
  type: enum
  values: [000, 001, 002]
  description: "000 = +4 dBu, 001 = -10 dBV, 002 = toggle"

- id: polarity_response
  type: enum
  values: [000, 001, 002]
  description: "000 = positive, 001 = negative, 002 = toggle"

- id: clip_response
  type: enum
  values: [000, 001, 002]
  description: "000 = no pad, 001 = 18dB pad, 002 = 12dB pad"

Variables

# UNRESOLVED: variables for read/write parameters not explicitly separated from actions in source.
# All settable parameters documented as actions above.

Events

# UNRESOLVED: no unsolicited event notifications described in source.

Macros

# UNRESOLVED: no multi-step macro sequences described in source.

Safety

confirmation_required_for: []
interlocks: []
# UNRESOLVED: no safety warnings or interlock procedures in source.

Notes

Serial string format: <D0h>DFR22<unit number><command><identifiers><sub-command><value><D1h>

• Prefix byte: D0h (208 decimal)
• Suffix byte: D1h (209 decimal)
• Unit number: 3-character device ID (e.g., "001")
• Omitting value triggers query; device returns current value

Gain table:

When "ALL" used for input commands: Separate response returned from each channel.

Provenance

source_domains:
  - content-files.shure.com
source_urls:
  - https://content-files.shure.com/KnowledgeBaseFiles/dfr22_rs232.pdf
retrieved_at: 2026-04-30T04:28:59.697Z
last_checked_at: 2026-06-02T22:14:23.281Z

Verification Summary

verdict: verified
checked_at: 2026-06-02T22:14:23.281Z
matched_actions: 26
action_count: 26
confidence: medium
summary: "All 26 spec actions traced to source (dip-safe re-verify). (10 unresolved item(s) noted in Known Gaps.)"

Known Gaps

- "device may support additional models in DFR Series (e.g., DFR8) — not documented in source"
- "exact response string format for each query type not fully detailed in source."
- "variables for read/write parameters not explicitly separated from actions in source."
- "no unsolicited event notifications described in source."
- "no multi-step macro sequences described in source."
- "no safety warnings or interlock procedures in source."
- "firmware version compatibility not stated"
- "power on/off commands not present in source"
- "exact response format for QRY command not detailed"
- "error codes/negative acknowledgements not documented"

From the AI4AV catalog (https://ai4av.net) · ODbL-1.0