RS232 Disk Drive, USB drive, disk storage, mass storage nonUSB, non-USB
MSTOR - RS232 Disk Drive Interface
by Versalent
MSTOR - Mass Storage Adapter -- a low-cost, small USB host module with an embedded disk file system that brings USB drives to any non-USB system with a UART .     A simple command set lets you read/write/modify files and navigate and manage a directory structure with simple RS232 commands. Battery-backed real time clock provides file timestamps that are automatically managed. The FAT file system is PC compatible! A companion configuration program provides access to setup features.
Intended usage: Mstor was designed for local or distant data storage. The relatively slow RS232 link generally precludes its use as an application code repository or boot device.
RS232 Disk Drive
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MSTOR Datasheet by Versalent

MSTOR    RS232 Disk Drive Interface to USB drive

  • RS232 interface to standard USB drives, FAT formatted, PC compatible
  • Includes a 4 gig USB drive
  • Onboard battery backed real-time clock
  • Low cost and small: 3" X 2" X 1"
  • Easily added to existing systems.
  • 20uA SLEEP mode allows battery operation
  • 11k byte/second access speed


  • Small systems without USB needing large/removal storage
  • nonUSB systems requiring data/file portability with a PC
  • Systems requiring remote/physically protected storage
  • Long term data logging
  • Add storage to existing systems

       MSTOR is a small module that brings up to 16 gig of standard mass storage to computer systems that provide no USB ports. The embedded file system allows a user to send simple commands to List Files and Directories, Read/Write/Append or Delete Files, Make/Delete Directories and more ... on a USB drive using one-character commands. A companion program for Windows is provided to configure MSTOR and exercise all its features. Full manual here

Command Example to READ a file:


Response:   MSTOR streams a selectable group-size of characters from the specified file in response to each single character group-request.
(Or -- request CRC'd message blocks using block-request/block-answer sequencing).
-- 5V Models --
MSTOR-014(DCE) 5VDC power on pin 4 DB9
MSTOR-016(DCE) 5VDC power on pin 6 DB9
MSTOR-034(DTE) 5VDC power on pin 4 DB9
MSTOR-036(DTE) 5VDC power on pin 6 DB9
-- 6-9V Models --
MSTOR-024(DCE) 6-9VDC power from wall-brick
MSTOR-044(DTE) 6-9VDC power from wall-brick
Note: DCE Models plug directly into COM port with no pin-swaping
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RS232 Disk Drive, USB drive, disk storage, mass storage nonUSB, non-USB