DF Report

DF Report - Diagnostic Faults (ECU faults)

Carries the full list of active faults reported by the vehicle’s computer — J1939 on trucks and machinery, OBD2 on light vehicles — with the date and time the fault appeared.

It is generated in three ways:

Automatically, when a new fault appears or all of them clear, if the CXDTC module has autorpt=1.
On demand, with >QDF< (direct response) or >GDF00H< (queued to the destination).
From a rule in the event engine: ACC={GDF00H}.

Every report is a full snapshot of the state: the platform never needs to rebuild anything or keep track of which fault was added or removed.

DF report format


>RDF[NN][DDMMYY][HHMMSS];[n][;fault;fault;...]<

Report fields

Field	Description
NN	Report number (00-FF)
DDMMYY	Date of the fault
HHMMSS	Time of the fault
n	Number of active faults (`0` = resolution: none left)
fault	Each fault as `<source>:<ecu>:<code>:<fmi>:<occurrences>`

Date and time are those of the event, not of transmission. If the vehicle was out of coverage, the report waits in the device queue and reports when the fault actually occurred once signal returns.

Examples


// Truck (J1939): two active faults
>RDF00020826143512;2;J:00:100:1:4;J:00:1761:1:12<
 
// Light vehicle (OBD2): one active fault
>RDF00010926104233;1;O:00:P0301:0:0<
 
// Resolution: all faults cleared
>RDF00020826150233;0<

Reading the first example: the engine ECU (00) reports oil pressure (SPN 100) below the normal range (FMI 1), which occurred 4 times, and low AdBlue/urea level (SPN 1761), 12 times.

Structure of each fault


J:00:100:1:4
│ │  │   │ └─ occurrence count
│ │  │   └─── FMI: how it fails
│ │  └─────── SPN: which component fails
│ └────────── reporting ECU (hex)
└──────────── source: J = J1939 · O = OBD2

Source	Code	FMI	Occurrences
`J` (J1939)	Numeric SPN (`100`, `1761`)	0-31	0-127
`O` (OBD2)	SAE J2012 standard code (`P0301`, `U0100`)	always `0`	always `0`

FMI and occurrence count are J1939-specific fields: the OBD2 protocol does not transmit them.

DF versus RDTC

The >QDTC< query answers with the RDTC prefix and the same list, but without date or time. The different prefix is deliberate: it lets the server tell a spontaneous report from a command response without counting characters.

	`RDF`	`RDTC`
Origin	Report (automatic, `QDF`, `GDF` or rule)	Response to `>QDTC<`
Date and time	Yes, of the event	No
Queue, retries and ACK	Yes	No, answers over the asking channel

Limits

Limit	Value
Simultaneous faults in the device table	32
Faults per frame	~15 — the reported count (`n`) is always the real one, the list is truncated
Minimum interval between automatic reports	10 s

Signal	Description
`DTC00`	There is at least one active fault
`DTC01`	A new fault appeared
`DTC02`	A dashboard lamp is on (J1939 only)
`DTC03`	All faults were cleared

Compatibility

💾Firmware:v1.09.27

SP-IOT

SM-IOT

Rinho Zero IoT has no CAN transceiver: it does not generate this report.

The 1.09.27 series is, at the time of publishing this page, a T (pre-release) version delivered via FOTA on request. OBD2 support arrived in T9; with an earlier T the device only reads J1939 faults.