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P104-COM232-8 and 104I-COM232-8

PC/104-Plus and PCI-104 8-Port RS-232 Serial Communication


  • High Performance Octal PCI UART
  • 16550 Compatible Register Set
  • Up to 460Kb/s Serial Data Rate
  • Global Interrupt Source Register
  • Data Transfer in Byte, Word, and Double-Word
  • 64-Byte Transmit and Receive FIFOs per each of eight UARTs
  • Transmit and Receive FIFO Level Counters
  • Programmable Trasmit and Receive FIFO Trigger Level
  • RoHS Available. Please contact us for ordering information
  • Designed, made, supported, and manufactured in the USA
The P104-COM232-8 (PC/104-Plus) and 104I-COM232-8 (PCI-104) are PC/104-based eight channel RS-232 communication peripherals. Based on the XR17D158, the boards have eight enhanced 16550 UARTs, each with a set of modem signals (CTS, RTS, RI, DTR, DSR, CD). A 460Kb/s rate is guaranteed for all channels with up to 3K Ohm 1000pF loads. All interrupts may be monitored at a 32-bit status register. Each UART has both a 64 byte transmit and a 64 byte receive FIFO.

The typical quiescent current draw from the user's 5V supply is less than 60mA (with P1 and P2 disconnected). If every transmitter line is loaded with 3K Ohm, current draw should still be less than 150mA.

Linux drivers and sample programs are supplied with the card.


The provided Windows drivers are 100% compatible with the normal Microsoft-provided Serial Application Programming Interface. This means every program you've ever used with a standard serial port in Windows will also work with these ports, no problem. In addition, we provide several utility and sample programs to help you write your own code, if you're not using something off-the-shelf.

Available Reference Manuals

Available Software Downloads

Drivers and Downloads

Full list of available Downloads: Software Packages, Drivers, Manuals, and other documents

Custom Software

ACCES also offers Custom Software Services for our products. Our prices are unbelievably low, often as inexpensive as free! If you need something tweaked to support your needs, or an entire enterprise application developed from scratch, it is definitely worth your time to inquire with us, first.

Further information about available ACCES Software:

Redistributing Windows Drivers
A list of ACCES drivers and the files that compose them under different versions of Windows, so you can easily redistribute ACCES cards and drivers.



  • PCI Bus: Rev. 2.3
  • PC/104 Bus: Feedthrough only, no connection to the P104-COM232-8
  • I/O Space: Requires 4k

16550 Compatible

  • Data Size: 5, 6, 7 or 8 bits
  • Stop bit length: 1, 1.5 or 2 bits
  • Parity: Odd, even, none, forced to 1, or forced to 0
  • Break condition: On or off
  • Maximum Baud Rate: 460.8Kb/s (transceiver limit with full load)
  • Full Duplex Operation
  • Eight 64 Byte Transmit FIFO, 64 Byte Receive FIFO (16C550 FIFO = 16 Bytes)
  • S/W programmable FIFO trigger levels (16C550 trigger levels are fixed)
  • 12 standard registers for UART monitoring and control plus special registers
  • Loop-back mode
  • Scratch pad register

Transceiver I/O Characteristics

  • Receiver Input Resistance: 3K to 7K ohm
  • Receiver Input Sensitivity: ±3V
  • Receiver Input Voltage Range: ±15V
  • Driver Slew Rate: 30V/µS
  • Driver Load Impedance: 3K to 7K ohm
  • Driver Output Signal Level
    • Loaded ±5V
    • Unloaded ±15V
  • Transceiver ESD Characteristics
    • ±15KV Human Body Model
    • ±15KV Air Discharge
    • ±8KV Contact Discharge
  • Communications Interface: Eight channels split between two 40 pin male headers
  • Meets or exceeds the IEEE RS-232 standard


  • Operating Temperature Range:
    • Commercial: 0° to 70°C
    • Industrial: -40°C to +85°C
  • Humidity: 5% to 95%, non-condensing
  • Storage Temperature Range: -65°C to +125°C
  • Power Required: 50mA quiescent, 150mA maximum
  • Size: PC/104-Plus format, 3.5" x 3.75"

CE testing & approval must be done at the system level, in the designed enclosure, and is not done on individual boards.

ModelPrice (USD)

Ordering Guide
P104-COM232-8PC/104-Plus 8-port RS-232 serial communication board
104I-COM232-8PCI-104 (no ISA connector) 8-port RS-232 serial communication board
C104-40F-D9M40 pin ribbon cable with female header to 4 DB9M connectors, 12" long $25
C104-40F-1240-pin ribbon cable with female headers, 12" long $12
C104-40F/D37F40 pin ribbon to DB37 female cable $17.50
104-HDW-KIT(X)Specify metric (M) or standard (S) hardware kit. Includes 4 screws, nuts and standoffs $10
104-SPC-KITPC/104 spacer kit includes 16-bit pass-through connector and hardware kit $20
MP104-DINDIN-rail mounting provision $19
ADAP9Screw terminal adapter (single DB9 female to 9 screw terminals) $19
ADAP9-2Screw terminal adapter (dual DB9 female to 18 screw terminals) $25
PCI-P104-ADAPPCI to PC/104-Plus adapter card permits a PC/104-Plus board to be installed in a PCI slot $129
Options (call for pricing)
-TExtended operating temperature (-40°C to +85°C)
-RoHSRoHS compliant version
-CallContact ACCES with your special requirement

Acquisition, Control, Communication: Engineering and Systems