Why do I get a "module already used" error from my SCI Receive block in External mode?

I have a Simulink model with multiple SCI Receive and Transmit blocks in it that I would like to run in external mode on my TI Launchpad (Delphino F28379D) board.

However, when I attempt to generate and run the code I get the following error message:

Error evauating 'InitFcn' callback of C28x SCI Receive Block (mask)
Callback string is c28sxci_callback('renderDisplay')
validateC280xSCI('Rx');
codertarget.registry.registerC2380xSCIRxBlocks(gcb);

Caused by:
- The SCI Module A is already used by another block or by External mode

Answer 1

[MathWorks Support Team]

This error message indicates that two blocks within the module (Tx and Rx in this instance) were trying to communicate using the same SCI Module (module A). 

To resolve the error, switch one of the Receive blocks to use a different SCI module (module B for instance).

The reference page for C28x SCI Receive states "a model can only contain one SCI Receive block for each module."

https://www.mathworks.com/help/releases/R2022b/supportpkg/texasinstrumentsc2000/ref/c28xscireceive.html?searchHighlight=sci%20port%20a&s_tid=doc_srchtitle