I have been using the nrf24L01 and I have been successful with having one unit send and another unit receive. I have used this wiki as a guide, https://arduino-info.wikispaces.com/Nrf24L01-2.4GHz-HowTo but it does not show anything about simultaneously sending and receiving with two of the units. I would use this for a small project involving two potentiometers where one potentiometer would be connected to one of the nrf24L01 modules and transmit its value to the other nrf24L01 module. Another potentiometer would be connected to the other nrf24L01 module and would transmit its value to the original nrf24L01 module. Is it possible to simultaneously send and receive values between the two nrf24L01 modules?
Is it possible to simultaneously send and receive values between the two nrf24L01 modules?
No.
Simultaneous transmitting and receiving requires you to use different frequencies separated by quite a lot, maybe even 1.6MHz. It also requires special notch filters to stop the transmitter deafening the receiver.
Would it be possible to have the nrf24L01 modules switch between being a sender and a receiver in a loop?
Yes, that is known as half duplex.
Depending on exactly your application you might want a master slave protocol where only one system initiates data transfer and the other responds. A bit like I2C protocol.