Multiplexing 24V signals to DC load generator
There are simple ways like a relay board, but if you want to use mosfets here is one option.
You can just get two of these(Any multiplexer will do as long as there are 30 total outputs.), 30 p-mosfets capable of 10A, 30 level shifters, and a raspberry pi/arduino/beaglebone.
You can make this cheaper, but more time consuming if you only do half of the outputs at a time.



simulate this circuit &ndash; Schematic created using CircuitLab
NOTES:
There are many factors that go into choosing a mosfet. VGS and RDSOn are the most important in your case because we are dealing with a DC high current signal.
EDIT: Also Vgs is important in your case because you have a 24 V signal most mosfets are only 20V rated. I have updated the schematic to include a voltage divider for the gate.
There are multiplexers that work with communication protocols like I2C and that is another option if you are running low on outputs.