In the Digi XBee LPX 900 RF Module specifications (specifically the Networking Topologies section), it mentions that it is “SX protocol compatible”. What is this referring too? Does this mean that it is compatible with the Digi Xbee SX 900 RF Module?
Yes, that is what it means.
Thanks for the help! So, just to clarify the XBee LPX 900 is compatible with both the XBee PRO 900Hp and the XBee SX modules, but the PRO 900Hp and XS modules are not compatible with each other?
Additionally, does this mean that the Digi XBee XR 900 is compatible with the XBee SX modules?
It does not use the same firmware for both compatibilities. You must use a specific firmware version for each of the different protocols. That is to say, you must use one firmware version for the HP and a different one for the SX.