It appears that this program is unable to communicate with an R5C and has difficulties with a Rebel XS.
Canon lists several cameras that do not permit full remote control
EOS M100 EOS M6 EOS M5 EOS M10 EOS M3 EOS M2 EOS M
This program uses a Software Development Kit (SDK) provided by Canon. Problems occurring in the SDK (such as the lack of compatibility with the R5C) are beyond my ability to solve. Canon provides the following list of which cameras the SDK supports. Note that I have only tested with three of the cameras on the list; the EOS 60Da, a modified EOS 80D, and an R8. If you plan to use one of the other cameras on the list it is YOUR responsibility to make sure it really works. To prevent surprises at the eclipse site the program requires that the camera passes the "Test Delay" before the program can confirm you will not lose images.
Some Canon cameras have mechanical shutters whose maximum speed is 1/4000. This version of CE is able to adapt so those (in theory) are no longer a problem. However, I have no ability to test these so if a user has one and has a problem then please let me know.
As of this writing the following cameras are known to have shutter speeds limited to 1/4000. Note this list may not be exhaustive. Check your camera.
Full time use of the electronic shutter is not recommended due to the electronic shutter limiting the pixel depth of the image.
R Cameras with special support
For the following cameras CE will automatically switch to electronic shutter when shooting burst and/or exposures of 1/8000. The program will also allow the program to set the camera clock although Canon only claims support for this in R5 and R6 (I have verified correct operation in an R8)
The following Canon Cameras have a maximum EFCS shutter speed of 1/4000; however, in electronic shutter mode they can operate at 1/8000. CE will automatically switch to electronic shutter.
Cameras that support setting time
In addition to the cameras above, according to Canon, the following allow CE to set the camera's time
This is the Canon list of supported cameras in SDK 13.19.0_Macintosh
EOS R6 Mark III EOS R50V EOS R1 EOS R5 Mark II PowerShot V10 (Firmware version 1.1.0 or later) EOS R100 PowerShot ZOOM (Firmware version 1.1.2 or later) EOS R50 EOS R8 EOS R6 Mark II EOS R10 EOS R7 EOS R3 EOS Kiss M2 / EOS M50 Mark II EOS R5 EOS R6 EOS Kiss X10i / EOS Rebel T8i / EOS 850D EOS Ra EOS-1D X Mark III EOS M200 EOS M6 Mark II EOS 90D PowerShot G7X Mark III PowerShot G5X Mark II EOS Kiss X10 / EOS Rebel SL3 / EOS 250D / EOS 200D II EOS RP PowerShot SX70 HS EOS R EOS Kiss M / EOS M50 EOS Kiss X90 / EOS REBEL T7 / EOS 2000D / EOS 1500D EOS REBEL T100/EOS 4000D / EOS 3000D EOS M100 *1 EOS 6D Mark II EOS Kiss X9 / EOS Rebel SL2 / EOS 200D EOS Kiss X9i / EOS Rebel T7i / EOS 800D EOS 9000D / EOS 77D EOS M6 *1 EOS M5 *1 EOS 5D Mark IV EOS-1D X Mark II EOS 80D EOS Kiss X80 / EOS Rebel T6 / EOS 1300D EOS M10 *1 EOS 5DS EOS 5DS R EOS 8000D / EOS REBEL T6sEOS 760D EOS Kiss X8i / EOS REBEL T6i / EOS 750D EOS M3 *1 EOS 7D Mark II EOS Kiss X70/EOS 1200D/EOS REBEL T5/EOS Hi EOS M2 *1 EOS 70D EOS Kiss X7 / EOS 100D / EOS REBEL SL1 EOS Kiss X7i / EOS 700D / EOS REBEL T5i EOS-1D C EOS 6D EOS M *1 EOS Kiss X6i / EOS 650D / EOS REBEL T4i EOS-1D X EOS 5D Mark III EOS Kiss X50 / EOS REBEL T3 / EOS 1100D EOS Kiss X5 / EOS REBEL T3i / EOS 600D EOS 60D EOS Kiss X4 / EOS REBEL T2i / EOS 550D EOS-1D Mark IV EOS 7D EOS Kiss X3 / EOS REBEL T1i / EOS 500D EOS 5D Mark II EOS 50D EOS DIGITAL REBEL XS / 1000D/ KISS F EOS DIGITAL REBEL Xsi / 450D / Kiss X2 EOS-1Ds Mark III EOS 40D EOS-1D Mark III