Service Interaction Protocol
Communication Control
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.
Control Logic
SID 0x28 acts as a gatekeeper for different message types. By specifying the Communication Type, you can selectively block application data while keeping network management alive, or vice-versa.
Selective isolation of Normal vs. Network Management communication paths.
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
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
Logic_Exceptions