DCC Command Station Protocol¶
TODO Review tables and commands
Complete reference guide for serial commands used with DCC command stations.
System Commands¶
| Command | Description | Parameters |
|---|---|---|
<#> |
Request number of simultaneously supported locos | None |
<!> |
Emergency stop all locos | None |
<s> |
Command station status | None |
<E> |
Store EEPROM | None |
<e> |
Clear EEPROM | None |
Power Control¶
| Command | Description | Parameters |
|---|---|---|
<1> |
Power ON all tracks | None |
<1 MAIN> |
Power on MAIN track | None |
<1 PROG> |
Power on PROG track | None |
<1 JOIN> |
JOIN prog track to MAIN and power | None |
<1 track> |
Power on given track | track: Track identifier |
<0> |
Power off all tracks | None |
<0 MAIN> |
Power off MAIN track | None |
<0 PROG> |
Power off PROG track | None |
<0 track> |
Power off given track | track: Track identifier |
Locomotive Control¶
| Command | Description | Parameters | Status |
|---|---|---|---|
<t loco> |
Request loco status | loco: Locomotive ID |
Active |
<t loco tspeed direction> |
Set throttle speed and direction | loco: ID, tspeed: 0-127, direction: 0/1 |
Active |
<t ignore loco tspeed direction> |
Set throttle speed and direction | Legacy format | ⚠️ Deprecated |
<- loco> |
Remove loco state and reminders | loco: Locomotive ID |
Active |
<-> |
Clear loco state and reminder table | None | Active |
Function Control¶
| Command | Description | Parameters | Status |
|---|---|---|---|
<F loco function onoff> |
Set loco function ON/OFF | loco: ID, function: Function number, onoff: 0/1 |
Active |
<F loco DCCFREQ freqvalue> |
Set DC frequency for loco | loco: ID, freqvalue: Frequency value |
Active |
<f loco byte1> |
Set loco function group | loco: ID, byte1: Function byte |
⚠️ Deprecated |
<f loco group byte2> |
Set loco function group | loco: ID, group: Group ID, byte2: Function byte |
⚠️ Deprecated |
Turnout Control¶
| Command | Description | Parameters |
|---|---|---|
<T> |
List all turnouts | None |
<T id> |
Delete turnout | id: Turnout ID |
<T id X> |
List turnout details | id: Turnout ID |
<T id T> |
Throw turnout | id: Turnout ID |
<T id C> |
Close turnout | id: Turnout ID |
<T id value> |
Close (value=0) or Throw turnout | id: Turnout ID, value: 0/1 |
<T id SERVO vpin closedValue thrownValue> |
Create servo turnout | id: ID, vpin: Pin, values for positions |
<T id VPIN vpin> |
Create pin turnout | id: ID, vpin: Pin number |
<T id DCC addr subadd> |
Create DCC turnout | id: ID, addr: Address, subadd: Sub-address |
<T id DCC linearAddr> |
Create DCC turnout | id: ID, linearAddr: Linear address |
<T id addr subadd> |
Create DCC turnout | id: ID, addr: Address, subadd: Sub-address |
<T id vpin closedValue thrownValue> |
Create SERVO turnout | id: ID, vpin: Pin, position values |
Sensor Control¶
| Command | Description | Parameters |
|---|---|---|
<S id vpin pullup> |
Create sensor | id: Sensor ID, vpin: Pin, pullup: Pull-up setting |
<S id> |
Delete sensor | id: Sensor ID |
<S> |
List sensors | None |
<Q> |
List all sensors | None |
CV Programming¶
| Command | Description | Parameters | Status |
|---|---|---|---|
<W cv value> |
Write CV value on PROG track | cv: CV number, value: Value |
Active |
<W loco> |
Write loco address on PROG track | loco: Address |
Active |
<W CONSIST loco> |
Write consist address on PROG track | loco: Address |
Active |
<W CONSIST loco REVERSE> |
Write consist address and reverse flag | loco: Address |
Active |
<W cv bitvalue bit> |
Write CV bit on prog track | cv: CV, bitvalue: Bit value, bit: Bit position |
Active |
<W cv value ignore1 ignore2> |
Write CV value on PROG track | Legacy format | ⚠️ Deprecated |
<R cv> |
Read CV | cv: CV number |
Active |
<R> |
Read driveable loco ID | None | Active |
<R cv ignore1 ignore2> |
Read CV value on PROG track | Legacy format | ⚠️ Deprecated |
<V cv value> |
Fast read CV with expected value | cv: CV number, value: Expected value |
Active |
<V cv bit bitvalue> |
Fast read bit with expected value | cv: CV, bit: Bit position, bitvalue: Expected |
Active |
<B cv bit bitvalue> |
Write CV bit | cv: CV number, bit: Bit position, bitvalue: Value |
Active |
<w loco cv value> |
POM write CV on main track | loco: ID, cv: CV number, value: Value |
Active |
<r loco cv> |
POM read CV on main track | loco: ID, cv: CV number |
Active |
<b loco cv bit bitvalue> |
POM write CV bit on main track | loco: ID, cv: CV, bit: Position, bitvalue: Value |
Active |
DCC Accessory Commands¶
| Command | Description | Parameters |
|---|---|---|
<a address subaddress activate> |
Send DCC accessory command | address: Address, subaddress: Sub-address, activate: 0/1 |
<a address subaddress activate onoff> |
Send DCC accessory command with on/off | address: Address, subaddress: Sub, activate: 0/1, onoff: 0/1 |
<a linearaddress activate> |
Send DCC accessory command | linearaddress: Linear address, activate: 0/1 |
<A address value> |
Send DCC extended accessory (Aspect) command | address: Address, value: Aspect value |
Momentum Control¶
| Command | Description | Parameters |
|---|---|---|
<m LINEAR> |
Set momentum algorithm to linear acceleration | None |
<m POWER> |
Set momentum algorithm based on speed difference | None |
<m loco momentum> |
Set momentum for loco (accel and braking) | loco: ID, momentum: Value |
<m loco accelerating braking> |
Set momentum for loco | loco: ID, accelerating: Value, braking: Value |
Output Control¶
| Command | Description | Parameters |
|---|---|---|
<Z> |
List output definitions | None |
<Z id pin iflag> |
Create output | id: Output ID, pin: Pin number, iflag: Invert flag |
<Z id active> |
Set output | id: Output ID, active: 0/1 |
<Z id> |
Delete output | id: Output ID |
Pin Control¶
| Command | Description | Parameters |
|---|---|---|
<z vpin> |
Set pin HIGH if vpin positive, LOW if negative | vpin: Pin number (signed) |
<z vpin analog> |
Write analog device value | vpin: Pin, analog: Value |
<z vpin analog profile> |
Write analog device using profile | vpin: Pin, analog: Value, profile: Profile ID |
<z vpin analog profile duration> |
Change analog value over duration | vpin: Pin, analog: Value, profile: Profile, duration: Time |
NeoPixel Control¶
| Command | Description | Parameters |
|---|---|---|
<o vpin> |
Set neopixel on (vpin>0) or off (vpin<0) | vpin: Pin number (signed) |
<o vpin count> |
Set multiple neopixels on/off | vpin: Pin, count: Number of pixels |
<o vpin r g b> |
Set neopixel colour | vpin: Pin, r: Red, g: Green, b: Blue |
<o vpin r g b count> |
Set multiple neopixels colour | vpin: Pin, r: Red, g: Green, b: Blue, count: Count |
Turntable Control¶
| Command | Description | Parameters |
|---|---|---|
<I> |
List all turntables | None |
<I id> |
Broadcast turntable type and current position | id: Turntable ID |
<I id position> |
Rotate a DCC turntable | id: ID, position: Position |
<I id DCC home> |
Create DCC turntable | id: ID, home: Home position |
<I id position activity> |
Rotate an EXTT turntable | id: ID, position: Position, activity: Activity |
<I id EXTT vpin home> |
Create an EXTT turntable | id: ID, vpin: Pin, home: Home position |
<I id ADD position value angle> |
Add turntable position | id: ID, position: Position, value: Value, angle: Angle |
JSON Commands¶
| Command | Description | Parameters |
|---|---|---|
<J M> |
List stash values | None |
<J M stash_id> |
Get stash value | stash_id: Stash identifier |
<J M CLEAR ALL> |
Clear all stash values | None |
<J M CLEAR stash_id> |
Clear given stash | stash_id: Stash identifier |
<J M stashId locoId> |
Set stash value | stashId: Stash ID, locoId: Loco ID |
<J M CLEAR ANY locoId> |
Clear all stash entries containing locoId | locoId: Locomotive ID |
<J C> |
Get fastclock time | None |
<J C mmmm nn> |
Set fastclock time | mmmm: Minutes, nn: Rate |
<J G> |
Report gauge limits | None |
<J I> |
Report currents | None |
<J A> |
List routes | None |
<J R> |
List roster | None |
<J R id> |
Get roster for loco | id: Locomotive ID |
<J T> |
Get turnout list | None |
<J T id> |
Get turnout state and description | id: Turnout ID |
<J O> |
List turntable IDs | None |
<J O id> |
List turntable state | id: Turntable ID |
<J P id> |
List turntable positions | id: Turntable ID |
Track Manager¶
| Command | Description | Parameters |
|---|---|---|
<=> |
List track manager states | None |
<= track MAIN> |
Set track to MAIN | track: Track identifier |
<= track MAIN_INV> |
Set track to MAIN inverted polarity | track: Track identifier |
<= track MAIN_AUTO> |
Set track to MAIN with auto reversing | track: Track identifier |
<= track PROG> |
Set track to PROG | track: Track identifier |
<= track OFF> |
Set track power OFF | track: Track identifier |
<= track NONE> |
Set track no output | track: Track identifier |
<= track EXT> |
Set track to use external sync | track: Track identifier |
<= track AUTO> |
Update track to auto reverse | track: Track identifier |
<= track INV> |
Update track to inverse polarity | track: Track identifier |
<= track DC loco> |
Set track to DC | track: Track ID, loco: Loco ID |
<= track DC_INV loco> |
Set track to DC with inverted polarity | track: Track ID, loco: Loco ID |
<= track DCX loco> |
Set track to DC with inverted polarity | track: Track ID, loco: Loco ID |
Configuration Commands¶
| Command | Description | Parameters |
|---|---|---|
<C PROGBOOST> |
Configure PROG track boost | None |
<C RESET> |
Reset and restart command station | None |
<C SPEED28> |
Set all DCC speed commands as 28 step | None |
<C SPEED128> |
Set all DCC speed commands to 128 step (default) | None |
<C RAILCOM ON> |
Enable Railcom cutout | None |
<C RAILCOM OFF> |
Disable Railcom cutout | None |
<C RAILCOM DEBUG> |
Enable Railcom cutout for scope testing | None |
<C WIFI "ssid" "password"> |
Reconfigure stored WiFi credentials | ssid: Network name, password: Password |
Diagnostic Commands¶
| Command | Description | Parameters |
|---|---|---|
<D ACK ON> |
Enable PROG track diagnostics | None |
<D ACK OFF> |
Disable PROG track diagnostics | None |
<D ACK LIMIT value> |
Set ACK detection limit mA | value: Current limit in mA |
<D ACK MIN value MS> |
Set ACK minimum duration mS | value: Duration in milliseconds |
<D ACK MIN value> |
Set ACK minimum duration µS | value: Duration in microseconds |
<D ACK MAX value MS> |
Set ACK maximum duration mS | value: Duration in milliseconds |
<D ACK MAX value> |
Set ACK maximum duration µS | value: Duration in microseconds |
<D ACK RETRY value> |
Set ACK retry count | value: Retry count |
<D CABS> |
Diagnostic display loco state table | None |
<D RAM> |
Diagnostic display free RAM | None |
<D CMD ON> |
Enable command input diagnostics | None |
<D CMD OFF> |
Disable command input diagnostics | None |
<D RAILCOM ON> |
Enable Railcom diagnostics | None |
<D RAILCOM OFF> |
Disable Railcom diagnostics | None |
<D WIFI ON> |
Enable WiFi diagnostics | None |
<D WIFI OFF> |
Disable WiFi diagnostics | None |
<D ETHERNET ON> |
Enable Ethernet diagnostics | None |
<D ETHERNET OFF> |
Disable Ethernet diagnostics | None |
<D WIT ON> |
Enable Withrottle diagnostics | None |
<D WIT OFF> |
Disable Withrottle diagnostics | None |
<D LCN ON> |
Enable LCN diagnostics | None |
<D LCN OFF> |
Disable LCN diagnostics | None |
<D WEBSOCKET ON> |
Enable Websocket diagnostics | None |
<D WEBSOCKET OFF> |
Disable Websocket diagnostics | None |
<D EEPROM numentries> |
Dump EEPROM contents | numentries: Number of entries |
<D ANOUT vpin position> |
Test analog output | vpin: Pin, position: Position |
<D ANOUT vpin position profile> |
Test analog output with profile | vpin: Pin, position: Position, profile: Profile |
<D SERVO vpin position> |
Test servo | vpin: Pin, position: Position |
<D SERVO vpin position profile> |
Test servo with profile | vpin: Pin, position: Position, profile: Profile |
<D ANIN vpin> |
Display analogue input value | vpin: Pin number |
<D HAL SHOW> |
Show HAL devices table | None |
<D HAL RESET> |
Reset all HAL devices | None |
<D TT vpin steps> |
Test turntable | vpin: Pin, steps: Step count |
<D TT vpin steps activity> |
Test turntable with activity | vpin: Pin, steps: Steps, activity: Activity |
Raw DCC Packets¶
| Command | Description | Parameters | Status |
|---|---|---|---|
<M ignore d0 d1 d2 d3 d4 d5> |
Send up to 5 byte DCC packet on MAIN track | ignore: Ignored, d0-d5: Hex bytes |
Active |
<P ignore d0 d1 d2 d3 d4 d5> |
Send up to 5 byte DCC packet on PROG track | ignore: Ignored, d0-d5: Hex bytes |
Active |
<c> |
Report main track current | None | ⚠️ Deprecated |
Speed Values
- 0: Stop
- 1-127: Variable speed (1=slowest, 127=fastest)
Direction Values
- 0: Reverse
- 1: Forward
Deprecated Commands
Commands marked with ⚠️ are deprecated and may be removed in future versions. Use the recommended alternatives where available.