What is the correct term for this type of USB Input devices?
Assumption: The question is about a device to transmit 32 or more digital inputs to a PC over USB.

The device you are looking for is a 32-port (or more) USB GPIO module:


Ideally with integrated pull-up or pull-down resistors, so the state of those limit switches can be directly sensed
Ideally with a USB HID interface so a bespoke USB device driver is not required


There are several such devices commercially available, such as:


Diolan PC-I2C/SPI/GPIO Interface Adapter DLN-1 includes pull-up resistors for each channel
Numato Lab 32 channel USB GPIO module



While the capabilities of these devices include both input and output, and on some channels analog input as well, the functionality in the question is a subset of these, and thus well served by these modules. 



Alternatively, an Arduino Mega (or clone) provides all this functionality, 54 GPIOs, plus flexible programmability. Thus it is a superset of the GPIO modules mentioned above. They are sold on eBay and other sites for under $15.



Add on a Mega Sensor Shield, and you will have 54 GPIOs available to you as separate 3-pin connector blocks each with GND, VCC and IO pin, each with the facility of programmable pull-up resistors internal to the microcontroller: