That's a good question ... I've never tried with the "cheaper" SD ones like I use.

I know you can with more expensive models, like the CF ones from StarTech.com. They have the M/S jumper on them and I know people who use them on the same cables.

For the most part, CF cards and SD->IDE adapters do not allow Master/Slave operation on the same ribbon. They dont want to share the channel.

There is an exception, in that Syba makes a dual CF->IDE adapter.

This combines both master and slave on the same device, and forces the CF cards to play together. Sadly, it itself needs a 2.5" to 3.5" IDE adapter to work in a normal system, but thats hardly a show stopper.

I have tried SD->CF adapters on it, and they don't play nice, sadly.

Pin 39 on a compactflash card is meant to be used to specify which IDE channel it uses: GND = master, VCC = slave.
Most adapters just ground the pin so they only work as master.
Some will provide a jumper, but cheap CF cards don't pay attention to the pin and only respond to commands for the master channel, or both master and slave. So they don't work either.
In the case of an SD->IDE adapter, there is almost certainly one of those FPGA based chips that is programmed to act as a SD->CF adapter. Given the quality of them in general, I wouldn't expect them to properly implement master/slave mode.

I have two USD601 IDE to SD Adapter. There are no dipswitches, they only work as single drive, and always detected as master.
If I chain them on the same ribbon, detection stop working. They become identified like "@@mory @@ard @dapter", or even BIOS freeze at detection.

The fc1307 sd-ide controller chip that does most of the sinitechi sd-ide bridges supports master slave operations.
https://bitsavers.computerhistory.org/compone … 307/FC1307A.pdf

There are some sd-ide devices with a master slave switch.

If you don’t have the switch, there is a good chance it will still work in “cable select” mode with a C-sel cable. if you don’t have a csel cable, you can try removing pin 28 on one of the devices. If pin 28 is disconnected from ground, the device should be “slave”.