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M.2-COM-4SM Family


Four and Two-Port Multi-Protocol RS-232/422/485 M.2 Cards

US Prices
CDN Prices

Privacy and Security Policy


  • M.2 2260/2280 size with B & M keys and Latching I/O Connectors
  • Four- And Two-Port M.2 Serial Cards With Optional DB9M Connectivity
  • Four Software-Selectable Serial Types: RS-232, RS-422, And RS-485 (2Wire & 4Wire)
  • “SM” Models Support All 3 Serial Types. “S” Models Support RS-422 And RS-485
  • High Performance 16C950-Class UARTs With 128-Byte FIFO For Tx And Rx Buffering
  • Supports Data Communication Rates To 921.6Kbps In RS232 – As High As 3Mbps In Differential Modes – 10Mhz With Custom Crystal Option
  • Port-By-Port Field Selectable Termination For RS422 & RS485 Applications
  • Virtually Any Custom Baud Rate May Be Configured By The User Via Register Settings, No Custom Oscillator Needed
  • ±15kV ESD Protection On All Signal Pins
  • Supports CTS, RTS, And 9-Bit Data Mode, Half- and Full-Duplex communications
  • RoHS And Industrial Temp (-40°C To 85°C) Both Standard
  • Support for Wind River VxWorks (call for ordering information)



The M.2-COM-4SM family of cards feature high performance 16C950-class UARTs. Available in 4-port and 2-port versions, each port is capable of communication speeds up to 921.6kbps in RS-232 (differential modes support speeds as high as 3Mbps) and has 128-byte deep transmit and receive FIFOs. Large FIFOs protect against data loss in multitasking operating systems, reduce CPU utilization, and improve data throughput, while reducing or eliminating inter-character or inter-packet pauses. The advanced integrated circuit with pre-scalar supports a wide variety of custom baud rates, and any rates not otherwise achievable can be supported via a custom factory-installed crystal oscillator (up to 10Mbps!).

RS-232, RS-422, or RS-485 can be software selected, per port, and the selection is stored in non-volatile memory for future use. If you don’t need that much flexibility you can order versions with only RS422/485 or even pure RS232. The RS232 ports provided by the card are 100% compatible with every other industry-standard serial COM device, supporting TX, RX, RTS, and CTS. RS422 mode uses the same transceivers as the RS-485 specification, allowing perfect 4-wire RS-422 and RS-485 compatibility – and the device supports full-duplex RS-485 4-wire.

Communication is possible either with custom application software, with off-the-shelf applications (such as HyperTerminal), or with provided samples and utilities, including WinRISC™ (“Windows Really Incredibly Simple Communication”).

The serial ports on the device are accessed using a low-profile, latching, 6-pin Hirose connector. Optional breakout cables are available, and bring each port connection to a panel-mountable DB9-M connector.


  • Health and Medical Systems
  • Point of Sale (POS)
  • Automated Retail Kiosks
  • Embedded Systems
  • Traffic Systems
  • Factory Automation and Process Control
  • Retail
  • Hospitality
  • Gaming
  • Kiosks

Special Order

Please contact ACCES with your precise requirement. Examples of special orders would be custom oscillators, conformal coating, custom software or product labeling, and more. We will work with you to provide exactly what is required.

Accessories and Connections

Available accessories include 4 or 2-port DB-9 cable kits and screw terminal board for quick and easy connectivity, as well as 2mm and 2.5mm mounting hardware. The ADAP9 accessory provides a screw terminal connection to break out the RS232, RS422, and RS485 signals on the DB9M connector.


A complete driver support package is provided including an easy-to-use Windows terminal program for testing your COM ports. This simplifies the verification of proper COM port operation. The card installs as standard COM ports in all operating systems including DOS, Linux (including Mac OS X) and 32-bit and 64-bit Windows. Additional drivers may be available for a wide variety of operating systems including Windows CE, VxWorks, Windows Embedded Standard, IoT, and more. Please contact the factory for compatibility with your specific OS.


PC Interface

M.2 2260/2280 with B & M keys

Communications Interface



I/O: Hirose DF57 6-pin, latching
Mating: Hirose DF57H-6S-1.2C

Serial Ports: 4 (or 2) per-port software selectable RS422 & RS485, and/or RS232 depending on model
UART: Quad 16C950 with 128-byte FIFO for each transmit & receive buffer
Baud Rates: up to 921.6k baud in RS-232 up to 3MBaud in differential modes advanced-prescaler allows a wide variety of unusual baud rates to be achieved. Up to 10Mbps via custom crystal option.
Character length: 5, 6, 7, 8 bits (contact factory for assistance with 9-bit data)
Parity: Even, Odd, None, Mark, Space
Stop Interval: 1, 1½, 2 bits
Flow Control: RTS/CTS (RS-232 only), Xon/Xoff, None



Operating Temperature: -40°C to 85°C
Storage Temperature: -65°C to 150°C
Humidity: 5% to 95%, non-condensing
Power required: 3.3VDC @ 1.6W (typical)
ESD Protection: ±15kV on all signal pins (IEC 61000)



Weight:6.4 grams
Size: length: 50.95mm (2.006″); width: 30.00mm (1.181″)


Regulatory Compliance

This product is designed to be in full compliance with CE requirements.






Available Software Downloads

Available Datasheets


Drivers and Downloads

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.


ACCES has successfully partnered with Wind River to bring our entire line of PCI and PCI Express Serial Communication cards to VxWorks 7! All ACCES plug-and-play serial cards are now supported with our VxWorks driver, including RS232, RS422, RS485 (2- and 4-wire) and baud rates up to 10Mbps.

Designed as an update to the existing vxbPciNs16550Sio.c driver, we've added support for ×8 baud rates, proper handling of the unique register location of the 4th port in the Pericom PI7C9X7954 UART, and configuring the serial protocol from your application software.

With this driver suite all ACCES PCI, PCI Express, PCI Express Mini Card, M.2, PCI-104, PCIe/104, and all related "PCI Style" plug-and-play serial cards will detect and install as standard VxWorks SIO ports.



OEM and Volume Pricing Call - 1-877-902-2979

Model Price (USD)

M.2-COM-4SM 4-port, RS-232, -422, and -485 PCI Express Mini Card
M.2-COM-2SM 2-port, RS-232, -422, and -485 PCI Express Mini Card
M.2-COM-4S 4-port, RS-422, and -485 PCI Express Mini Card
M.2-COM-2S 2-port, RS-422, and -485 PCI Express Mini Card
M.2-COM232-4 4-port RS-232 PCI Express Mini Card
M.2-COM232-2 2-port RS-232 PCI Express Mini Card
All models ship standard with extended temp and RoHS
CAB-M.2-COM4 Four port DB9 male cable accessory kit
CAB-M.2-COM4-IP67 Four port DB9 IP67 male cable accessory kit
CAB-M.2-COM2 Two port DB9 male cable accessory kit
CAB-M.2-COM2-IP67 Two port DB9 IP67 male cable accessory kit 
ADAP9 Screw terminal adapter (single DB9 female to 9 screw terminals)
M.2-HDW-KIT2 2mm mounting hardware kit
USA Office

Address: 1480 Gulf Road, Suite 837,
PO Box 1280
Point Roberts, WA 98281

Western Canada - Vancouver BC

Tel:1.800.663.6001 or 1.604.925.6150
Address: 2454 Haywood Ave
West Vancouver, BC V7V 1Y1

Eastern Canada - Markham, Ontario

Tel:1.800.465.0164 or 1.905.513.7027