DIALOG: log UDS and OBD diagnostic data

Configure a REBEL LT or REBEL CT to poll a module over UDS (ISO 14229) or standard OBD-II. The logger then records parameters that are never broadcast on the bus.

Before you start

• A REBEL LT or REBEL CT, its USB cable and a cable to the vehicle (the Influx Technology OBD cable connects to CAN 0).
• DIALOG installed, with a project open. For projects and configurations, see DIALOG: create projects and configurations and send them to a REBEL.
• The module identifier and tester identifier for the module you want to read, and the bit rate of its network.
• The parameters to read: an ODX file from the module supplier, or the PID numbers and their scaling.

You set up UDS and OBD logging in DIALOG Configurator and above, the versions that import ODX files and edit PIDs. If the terms are new, read understanding UDS and on-board diagnostics basics first.

The videos in this guide show an earlier version of DIALOG (formerly DiaLog), so some menus look slightly different.

Create the configuration and the bus

1. Create a configuration. Select New Configuration and enter a name.
2. Check the sleep mode. On the Sleep Mode tab, choose the mode you need from the drop-down list. Clear Limit Module Wakeup so polling does not keep waking the vehicle and draining its battery. Select OK.
3. Add the bus. Select New Bus, choose CAN 0 (HS) and select OK. Use CAN 0 when you connect through the Influx Technology OBD cable.
4. Set the bit rate. Choose the bit rate of the vehicle network from the Bus Speed list and select OK.

Add the diagnostic protocol

Choose a preset

1. Add a protocol. Select New Protocol, choose Diagnostic and select OK.
2. Choose the preset. The Diagnostic Protocol Presets window lists these presets:
   • Bosch ISO14229
   • Conti ISO14229
   • ISO14230
   • ISO15765
   • Keyword2000
   • OBDII
   • Siemens ISO14229
   Choose the one that matches the module and select OK. The right-hand panel shows what the preset sets. For example, the Bosch ISO14229 preset uses an extended diagnostic session with module ident 0x7E8 and tester ident 0x7E0.

Set the module and tester identifiers

The Edit Diagnostic Protocol window opens on the ISO Settings tab. Enter the Module Ident (the CAN identifier the module answers on) and the Tester Ident (the identifier the logger sends requests on). Unless the module's documentation says otherwise, leave the flow control and timing fields at the preset's values. These are FS, ST Min, BS Max and Keep Alive Tick. To poll more than one module, select Add Module under Other Modules.

UDS or OBD: the Send start session box

Send start session makes the logger request a diagnostic session from the module (service 10, DiagnosticSessionControl) before it starts polling.

• UDS (ISO 14229): tick Send start session, so the module is in the session your identifiers need, then select OK.
• Standard OBD-II PIDs (mode 01): clear Send start session and Sample Only Valid PIDs. An OBD request needs no session. These two boxes are the first thing support checks when an OBD configuration records nothing.

Watch: Quick OBD configuration, out of the box (2:10)

Add the PIDs

Import them from an ODX file

1. Open Load ODX. On the Import tab, select Load ODX.
2. Choose the file. Select the ODX file, then select Open. DIALOG reads ODX, GDX and MDX description files.

Add a PID by hand

On the Configuration tab, open the New PID menu and select New PID. The same menu offers Import PID From Presets, New Address and Edit PID Presets. Fill in the New Data Item window and select OK.

Data Item, Units

The name and unit the recording shows.

PID, Mode

The identifier in hex and the diagnostic service that reads it.

Min Value, Max Value

The permitted range of the converted value.

Log on change, Rate

Log All Data records every sample. Rate sets how often the PID is polled.

Data Type, Msg Size, Byte Position, Byte Order, Bit Mask

Where the value sits in the reply and how to read it.

Conversion Method

A formula of the form (Ax + B) / (Cx + D), set with coefficients A to D, or a conversion table.

Watch: How to log data using UDS in DIALOG (1:33)

Edit the PID presets

The PID Presets window holds the library of predefined PIDs that Import PID From Presets draws on. To open it, select Edit PID Presets.

To find a preset, filter by PID, label, units, data type or mode. Select it and change its settings on the right. Then select Post to save or Cancel to discard.

Add and Delete manage single presets. Delete All Mode 0x22 removes every mode 0x22 preset from the library. Import ODX and Export ODX load or save the library.

PID settings

PID (Hex)

The hexadecimal identifier of the PID.

Label

The name of the preset.

Units

The unit of the converted value.

Mode

The diagnostic service used to read the PID.

Formula

A conversion formula applied automatically.

MinValue, MaxValue

The minimum and maximum permitted values.

Memory layout

Data Type

The data type of the value.

Size

The number of bytes in each data item.

Byte Position

Where the first data byte sits in the returned CAN message.

Start Bit, Bit Count

The first bit and the number of bits, for values that do not fill whole bytes.

Precision

The number of decimal places shown.

Byte Order

The order in which the data bytes are transmitted.

Send the configuration to the logger

1. Connect the logger. Plug the REBEL into the PC with the USB cable.
2. Send the configuration. Right-click it and select Send Configuration to the Logger, then select Yes.
3. Wait for the processing to finish. The logger runs the new configuration once DIALOG reports it is done.

If no diagnostic data is recorded

• Check the Tester Ident and Module Ident on the ISO Settings tab.
• Check that the vehicle supports the PIDs you added. For the standard OBD-II PIDs, see DIALOG reference: glossary, OBD and UDS services, ISO-TP and PIDs.
• For OBD-II, clear Send start session and Sample Only Valid PIDs.
• If the configuration also holds a CCP or XCP protocol, the logger only polls diagnostics once the CCP or XCP connection is up. See DIALOG: log ECU data over CCP or XCP from an A2L file.

If you are still stuck, contact technical support with the configuration and a short log file.

Next: DIALOG: log ECU data over CCP or XCP from an A2L file.