New Four Port Serial Interface Adds RS-232/422/485 Ports to PCI Express Bus

Sealevel Systems, Inc. introduces the new COMM+4.PCIe serial interface, which delivers the ultimate flexibility for expanding serial communications in a variety of test and measurement, process control and point-of-sale applications.

The COMM+4.PCIe serial interface provides four multifunction serial ports, each individually field-configurable for RS-232, RS-422, or RS-485. Each serial port utilizes a 16C954 UART with 128-byte Tx/Rx FIFOs that enables data rates to 921.6K bps for reliable high-speed communications in data-intensive applications. This high-performance UART includes 9-bit framing support and is register compatible with legacy software applications designed for 16C550 UARTs. In addition, the board derives a 62.5 MHz clock from the PCI Express bus. This ultra-high-speed clock is divided by a flexible 8-bit clock prescaler with 1/8 steps to provide support for the widest range of standard and non-standard baud rates.

In RS-485 mode, the board provides automatic control of the RS-485 driver in hardware, allowing the 7404e to be used with standard serial communications without the risk of bus contention and data corruption. Additionally, RS-485 network termination, critical to robust multi-drop communication, can be selectively added to the circuit via DIP-switches. In RS-232 mode, all modem control signals are implemented for maximum compatibility with a variety of serial peripherals such as PLC’s, bar code readers, scales, and other data acquisition/control devices.

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