The Serial Card is one of the card types in the DeltaV Explorer. You configure it as you would any other card. For example, you can plug in the card and have the system auto-sense it, or you can configure a placeholder for the card before connecting the actual card.
Each Serial Card has two ports. Each port can support as many as 16 serial devices.
The DeltaV Explorer help describes how to add Serial Cards to your I/O subsystem.