External Mode Timeout Error with Multiple TSG3 Blocks
R2026bIssue
When using multiple TSG3 blocks in a model, particularly on the Renesas RH850 U2B hardware board, you may encounter the following external mode error:
External Mode Open Protocol CheckData command failed
Caused by:
Multiple errors detected.
XCP internal error: timeout expired, in response to XCP SYNCH command
Error detected while trying to disconnect Simulink from target application.
XCP error: XCP internal error: No server connectedThis issue occurs because the TSG initialization function takes time on the Renesas RH850 U2B hardware board. When the model contains multiple TSG3 blocks, the combined initialization time can exceed the default external mode polling time, causing a timeout.
This issue can also occur when the sample time configured for DIO blocks is lower than the TSG carrier frequency.
Solution
Increase the Polling time parameter to a larger value to allow sufficient time for the TSG initialization to complete before external mode attempts to connect.
In the Simulink® model, on the Hardware tab, click Hardware Settings to open Configuration Parameters dialog box.
In the Configuration Parameters dialog box, navigate to Hardware Implementation > Target hardware resources > External mode.

Set the Set XCP target polling time parameter to Manually and then for the Polling time (in seconds) parameter, specify a larger polling time value (for example, 10 seconds or more).
Click OK and run the model in external mode again.
If the error persists, continue increasing the polling time value until the connection is established successfully.