Service Interaction Protocol
Comm Control
ISOLATION_TYPE
CONTROL_MODES
PERSISTENCE
Overview
“The CommunicationControl service is used by the client to switch on/off the transmission and/or reception of certain messages of the server.”
Primary Purpose
- Isolate target ECU for flashing
- Reduce bus load during diagnostics
- Disable Network Management (NM)
- Manage multi-node architectures
Critical Notes
Diagnostic communication is never disabled by this service. The ECU must always remain responsive to the tester.
Default Behavior
At ECU power-on, all communication (Normal and NM) is Enabled by default. Service 0x28 is used for temporary suppression of non-diagnostic traffic. Normal communication is restored automatically after an ECU reset or when the diagnostic session returns to Default Session (0x01).
Protocol Anatomy (Disable All)
◆ PROTOCOL ANATOMY
0x28 COMM CONTROL
0x28 RESPONSE
Sub-functions & Types
Control Types (Sub-function)
Value | Action | RX State | TX State |
|---|---|---|---|
| 0x00 | enableRxAndDisableTx | Enabled | Disabled |
| 0x01 | enableRxAndTx | Enabled | Enabled |
| 0x02 | disableRxAndEnableTx | Disabled | Enabled |
| 0x03 | disableRxAndTx | Disabled | Disabled |
Communication Types
Specified in the second byte of the data parameter.
Value | Name | Description |
|---|---|---|
| 0x01 | NormalComm | Application data (RPM, Speed, etc.) |
| 0x02 | NM | Network Management messages |
| 0x03 | All | Both Normal and NM messages |
Examples
Full Isolation (Pre-Flash)
Request
28 03 03> Disable RX/TX for All message types
Response
68 03> Isolation successful
Restore Normal Communication
Request
28 01 03> Enable RX/TX for All message types
Response
68 01> Normal signaling resumed
Isolation Pattern
Isolating the network bus during critical maintenance or programming.
Firmware Update Isolation Sequence
8 stepsPersistence: Communication control is volatile. An ECU Reset (0x11) or session timeout (P3 timeout) will restore normal communication automatically.
Negative Response Codes
Error_Catalog