DauntlessOBD Supported ELM327-Style “AT” Commands

In addition to offering our own enhanced commands for additional capabilities and ease of use, DauntlessOBD also supports the vast majority of ELM327 v2.2 “AT” command that pertain to the CAN protocol (excluding J1939). This enables it to work easily with many existing OBD applications, and to be more familiar to advanced users who interact with it via a serial terminal.

See also: DauntlessOBD Developer & API Info

Below is a summary of the “AT” portion of supported commands:

CommandNameStatusNotes
<CR>Repeat Last CommandSupportedSend a carriage return to repeat the last command sent (with a few exceptions)
(hex)Send CAN / OBD Message and Report ResultsSupportedSee also “DD AH” and related for automatic ISO-15765 response parsing and multi-frame CAN message capability
AT ALAllow Long MessagesNo EffectNo impact for CAN protocols; use “AT CAF” instead
AT AMCActivity Monitor CountSupportedReturned data may be of limited use
AT AMT …Activity Monitor TimeoutNo EffectDevice automatically manages its own power saving
AT ARAutomatically ReceiveSupported
AT AT 0/1/2Adaptive Timing Mode 0/1/2SupportedThis device includes additional advanced performance logic that is enabled here (and by default)
AT BDBuffer DumpNo EffectOld command for debugging; 13 zero bytes will be returned
AT BRD …Baud Rate DivisorNo EffectIrrelevant; relates to RS232 serial
AT BRT …Baud Rate TimeoutNo EffectIrrelevant; relates to RS232 serial
AT CAF 0/1CAN Auto Formatting Off / OnSupportedIf using an ISO-15765 protocol, DLC byte will automatically be handled
AT CEA hhCAN Extended AddressingSupported
AT CER hhCAN Extended Receive AddressSupported
AT CF hhh / hhhhhhhhCAN Filter ID PatternSupportedSingle “pass” filter; see “DD CRA” for multiple filters
AT CFC 0/1CAN Flow Control Off / OnSupported
AT CM hhh / hhhhhhhhCAN Filter ID MaskSupportedSingle “pass” filter; see “DD CRA” for multiple filters
AT CP hhCAN PrioritySupportedSets top 5 bits of CAN-29 header; older ELM command, as “AT SH” was later updated to also accepts the full 8 character hex value
AT CRARestore Default CAN FilterSupportedWhen sent with no parameter, resets filters to default
AT CRA hhh / hhhhhhhhCAN Receive Address FilterSupportedSet single “pass” filter for a specified address (3 or 8 hex characters), use ‘X’ character for wildcard; see “DD CRA” for multiple filters
AT CSCAN Status CountsSupported
AT CSM 0/1CAN Silent Monitoring Off / OnSupportedWill not send Acks or Errors, except for when waiting for a response after transmitting a request
AT CTM 1/5CAN Timer Multiplier: 1 or 5SupportedRelates to “AT ST”
AT CV …Calibrate Vehicle VoltageNo EffectObsolete; already factory calibrated
AT DSet DefaultsSupported
AT DLC 0/1CAN DLC Display Off / OnSupported
AT DPDescribe ProtocolSupportedDauntlessOBD Supported Protocol IDs
AT DPNDescribe Protocol by NumberSupportedDauntlessOBD Supported Protocol IDs
AT E 0/1Echo Off / OnSupported
AT FC SD …CAN Flow Control DataSupported1-5 bytes in hex format
AT FC SH hhh / hhhhhhhhCAN Flow Control HeaderSupportedRemember to call “AT FC SM 1” or similar to use
AT FC SM hCAN Flow Control ModeSupported
AT FEForget EventsNo Effect
AT H 0/1Headers Off / OnSupported
AT IELM Version IDSupportedReports like “ELM327 v2.2”; see also “DD I” for our actual device ID and version
AT IAReport Protocol is Active Y/NSupported
AT IGNVehicle Ignition MonitorSupportedData may be of limited use; simply reports “ON” when vehicle voltage is 10 volts or more
AT L 0/1Linefeeds Off / OnSupportedSends CR+LF instead of just CR
AT LPLow Power ModeSupportedCloses wireless connection and enters sleep mode until a wake event
AT M 0/1Memory Off / OnSupportedRemembers last successful auto protocol detection
AT MAMonitor AllSupportedSubject to filters set by CF/CM/CRA; recommended to use “DD MA” / “DD MF” instead for monitoring, or “DD SS” for an instant snapshot
AT MR hhMonitor ReceiverSupportedSingle byte parameter; subject to filters set by CF/CM/CRA and will update them if set; recommended to instead set filters and use “DD MF”
AT MT hhMonitor TransmitterSupportedSingle byte parameter; subject to filters set by CF/CM/CRA and will update them if set; recommended to instead set filters and use “DD MF”
AT NLNormal Length MessagesNo EffectNo impact for CAN protocols (use “AT CAF” instead)
AT PCProtocol CloseSupported
AT R 0/1Responses Off / OnSupported
AT RA hhReceive AddressSupportedSingle byte parameter, same as “AT SR”; may still be useful for CAN-29; see “AT CRA” for more control with CAN
AT RDRead Saved DataSupportedReads single byte that was saved via “AT SD”
AT RTRSend CAN RTR MessageLimitedWe’ve found that this feature may be of limited capability with our current CAN chipset
AT RVRead Vehicle VoltageSupported
AT S 0/1Spaces Off / OnSupported
AT SD hhSave DataSupportedSaves single byte that can be read with “AT RD”
AT SH hhh / hhhhhh / hhhhhhhhSet HeaderSupportedSets CAN-11 or CAN-29 transmit ID
AT SP h / hhSet ProtocolSupportedSee supported protocol list; supports 1 or 2 character protocol IDs; auto mode will only try OBD protocols
AT SR hhReceive AddressSupportedSingle byte parameter, same as “AT RA”; may still be useful for CAN-29; see “AT CRA” for more control with CAN
AT SSStandard Protocol Search OrderNo Effect
AT ST hhSet TimeoutSupportedNote that this is the maximum timeout when using Adaptive Timing modes
AT TA hhTester AddressSupportedSingle byte parameter; sets source address for CAN-29; see “AT SH” for more control with CAN
AT TP h / hhTry ProtocolSupportedSee supported protocol list; supports 1 or 2 character protocol IDs; auto mode will only try OBD protocols
AT V 0/1Set CAN Variable DLC Off / OnSupportedIf off, frames will be padded to 8 bytes
AT WSWarm StartSupported
AT ZResetSupportedEffectively same as “AT WS”
AT @1Device DescriptionSupported“Dauntless Devices OBD-II Interpreter”
AT @2Device IdentifierSupportedLast 12 characters of device serial number; use “DD SN” for full serial
AT @3Set the @2 IdentifierNot Supported@2 is factory set and cannot be changed