RocketPort ® EXPRESS 4J

RocketPort EXPRESS 4J multi-port serial card has RJ45 serial ports and is RS-232, RS-422, and RS-485 software-selectable.

Part Number: 31305-2

  • RJ45 multi-port serial expansion using a single PCIe slot maximizes host expansion capabilities; adds additional COM ports using only one slot
  • PCI Express x1, x2, x4, x8, x12 and x16 lane connectivity
  • Low-latency communication supporting the widest variety of applications
  • Support for the most popular Windows operating systems (including Windows® 10) and Linux kernels and QNX 6.x
  • Windows driver, which can be configured for interrupt or polling mode
  • RS-232, RS-422, and RS-485 software-selectable
  • On-board dedicated 44MHz RISC processor minimizes “host” CPU utilization
  • Edge-mounted RJ45 serial ports provide cost-effective, compact serial connections
  • Transmit and receive buffers 32 times larger than a standard 16550 UART-based serial card ensuring smooth, efficient data transfer
  • Free troubleshooting tools in the event you want to diagnose an issue:
    • Hardware diagnostics
    • LCOM (Linux tool for testing serial ports)
    • Comtrol Utility, which includes Test Terminal (WCOM2) for serial port testing and Port Monitor for monitoring ports

Comtrol’s RocketPort EXPRESS 4J serial port expansion card provides four “native” serial ports utilizing a single PCIe card slot and is compatible with all PCI Express bus architectures. The RJ45 serial ports, mounted on the edge of the card, support software configurable RS-232/422/485 serial communications at speeds up to 921.6 Kbps.

Every RocketPort serial card features the high-performance RocketPort processor chip, consisting of a dedicated 44MHz core that minimizes host CPU utilization and optimizes data transmission via larger transmitand- receive buffers than those of 16550 UART chips, commonly used in standard PC serial ports and low-end serial cards.

RocketPort technology enables these cards to outperform other serial expansion cards by handling the transmission of large amounts of data more reliably and efficiently.

Certified Windows drivers, support for the most popular operating systems, and readily available U.S.-based support makes the RocketPort 4J the perfect solution for projects requiring PC-based serial communication.

View Engineering Drawing

  • RocketPort Express 4J card
  • Loopback Plug
  • Maximum Cards/System 4
  • Bus Interface Specification PCI Express (PCIe) x1, x2, x4, x8, x12, x16-Lane Compatible
  • Board Dimensions 4.7" x 4.0"
    119.4 x 101.6 mm
  • Product Weight 2.9 oz
    82.21 g
Electrical Specifications
  • Current Consumption
    • +3.3VDC 910 mA
  • Power Consumption (maximum) 3.1 W
  • ESD Surge Protection Provides minimum of 15KV for all serial lines
Environmental Specifications
  • Air temperature
    • System On 0 to 60° C
    • System Off -20 to 85° C
  • Operating Humidity (non-condensing) 5% to 95%
  • Altitude 0 to 10,000 Feet
    3,048 m
  • Heat Output 10.6 BTU/Hr
  • MTBF (Mean Time Between Failures) 99.2 Years

Serial Communications

  • Connector TypeRJ45
  • Supported StandardsRS-232/422/485
  • Baud Rate 300 bps to 921.6 kbps
    • Receive Buffer 512 bytes
    • Transmit Buffer 512 bytes
  • Device Driver Data Control
    • Data Bits 5, 6, 7, or 8
    • Parity Odd, Even, None, Mark and Space
    • Stop Bits 1, 1.5, or 2
    • Flow Control Hardware or Software
Export Information
  • Packaged Shipping Weight0.8 lb
    0.36 kg
  • Package Dimensions 9.19" x 7.25" x 2.5"
    23.34 x 18.42 x 6.35
  • UPC Code 7-56727-99415-2
  • Schedule B Number 8471.80.1000

Device Drivers

  • Linux
  • Microsoft® Windows® 7
  • Microsoft® Windows® 2008 Server
  • Microsoft® Windows® Vista
  • Microsoft® Windows Server® 2003
  • Microsoft® Windows® XP
  • Microsoft® Windows NT® 4.0 (Legacy)
  • Microsoft® Windows® 2000 (Legacy)
  • FreeBSD® 5
  • FreeBSD® 6
  • QNX® 6.X
Regulatory Approvals
  • Emissions European Standard EN55022
    Canadian EMC requirements
    FCC Part 15 Subpart B
    Class B limit
  • Immunity European Standard EN55024
    IEC 1000-4-2/EN61000-4-2: ESD
    IEC 1000-4-3/EN61000-4-3: RF
    IEC 1000-4-4/EN61000-4-4: FAST TRANSIENT
    IEC 1000-4-5/EN61000-4-5: SURGE
    IEC 1000-4-6/EN61000-4-6: CONDUCTED DISTURBANCE
    IEC 1000-4-8/EN61000-4-8: MAGNETIC FIELD
    IEC 1000-4-11/EN61000-4-11: DIPS AND VOLTAGE VARIATIONS
  • Safety IEC 60950/EN60950
    CSA C22.2 No. 60950/UL60950 Third Edition
    European Standard: RoHS 2 Compliant under CE
  • Other Regulatory Approvals

  • Pinout Diagram

Find a Distributor

» Industrial Distributors
» North American Distributors
» International Distributors

Pre-Sales Questions

Comtrol's Pre-sales Team
For sales questions or to locate a reseller near you.

+1-800-926-6876 (1-800-Go Rocket)
Fax: +1-763-957-6001

Comtrol's Industrial Automation Sales
For sales questions or to locate an industrial distributor near you.

+1-800-926-6876 (1-800-Go Rocket)
Fax: +1-763-957-6001

DocumentDescriptionDownload File
RocketPort ® EXPRESS 4J User GuideContains detailed installation procedures and configuration information.
Product Support and Service Information

Part Number: 31305-2

Sales Support

Call +1.763.957.6000, or e-mail

Technical Support

For technical assistance, our U.S.-based technical support team is only a phone call away.

Call +1.763.957.6000, or visit our forum .


Comtrol offers a 30-Day satisfaction guarantee and a 5-year limited warranty on all RocketPort EXPRESS family products!

View Warranty

Extended Warranty Available

Software & Drivers
» Comtrol FTP Site