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January 31, 2003
From WinSystems, Inc.
Eight Serial I/O Ports on a Single PC/104 Module support 128-byte TX & RX FIFOs on all channels
Contact Name: Emily Beckner
Contact Email: firstname.lastname@example.org
WinSystems new PCM-COM8 is a PC/104-compliant, 8-channel serial RS-232/422/485 asynchronous communications module. It is designed for embedded applications requiring a large number of serial I/O ports while minimizing processor overhead. This is achieved by providing each individual transmit and receive channel a 128 byte deep FIFO. This increases the service interval by the CPU by almost a factor of 10 when compared to a standard 16-byte FIFO and greatly reduces the bandwidth requirement of the CPU. Also, four selectable levels of FIFO trigger interrupt and automatic hardware/software flow control streamline data throughput performance especially when operating in a multi-channel environment.
Two XR16C854 devices serve as the serial communication controllers. They are improved versions of the 16C554 UART with higher operating speeds, lower access times and larger FIFO memory. Each controller supports 5-, 6-, 7-, or 8-bit characters with even, odd or no parity generation and checking. Each device contains on-chip software programmable baud rate generators with data rates selectable through 115,200 bits per second. The serial channels can be set up to provide internal diagnostics such as loopback and echo mode on the data stream.
All eight channels support RS-232, RS-485, and RS-422 electrical levels to interface to a wide variety of serial communications devices such as modems, data collection equipment, and distributed I/O terminals. The RS-232 interface has a high ESD rating of 15kV. The RS-422/485 configuration provides separate balanced transmit and receive signal pairs. Resistor termination networks are on the PCM-COM8 board for impedance matching and biasing.
A custom bus interface chip provides for software control and retrieval of configuration settings in an onboard EEPROM. At power up, the PCM-COM8 loads these settings and automatically configures each channel without external intervention. The PCM-COM8 also supports shared interrupts reducing the number of limited IRQ lines required in a system.
The PCM-COM8 will operate over the full industrial temperature range of -40° to +85° Centigrade. It only requires +5 volts DC to operate.
PRICING AND AVAILABILITY
The PCM-COM8’s list price is $295. Delivery is stock to 3 weeks.