Besides X-Link, what do I need to buy to implement a gateway?

X-Link includes everything you need to implement a gateway with exception of interface cards, of which you may need one or more. The interface cards allow the X-Link to communicate over the networks. Some networks use standard mediums like RS-232, RS-422 or RS-485. X-Link has a built-in port that can be used in these cases without the necessity of purchasing a serial network interface card.