PCIe-COM-4SMDB and RJ Family Manual
6
Functional Description
These cards feature high performance 16C950 class UARTs which support the complete
register set of the standard 16C550-type devices. The UARTs support operations in 16C450,
16C550 and 16C950 modes. Each port is capable of data communication speeds up to
3Mbps (standard model up to 460.8kbps in RS-232 mode) in asynchronous mode and has
128-byte deep transmit and receive FIFOs to protect against lost data in multitasking
operating systems, to help reduce CPU utilization and to improve data throughput.
Serial protocol (RS-232/422/485) is software configured per port via a Port Configuration
Utility provided on the CD which ships with each card. When RS-485 is selected, jumper
selectable termination is provided per port.
Four-port “DB” models (PCIe-COM-4SMDB, PCIe-COM-4SDB, PCIe-COM232-4DB) ship with
a additional mounting bracket and cable. This plugs directly into the dual 10-pin IDC headers
on board and mounts to the next adjacent bracket slot.
A crystal oscillator is located on the card. This oscillator permits precise selection of a
multitude of different baud rates.
Figure 1-1: Block Diagram
