Table of Contents
Advertisement
DasyLab Platinum Modbus Interface
2.2.4 Modbus USB Support
The Modbus specification supports RS232 and RS485 serial data. For ASCII formatted packets a
USB virtual comm channel provides full support since the framing information is specified by unique
characters (SOF = ':', EOF = CR/LF).
For RTU formatted packets the Modbus requires specific inter-frame character timing to determine
the framing of each transaction. This information is not available using a generic virtual comm
channel across USB, which will typically collect 'serial' data into 64 byte packets for transmission, as
determined by the USB end-point buffer size. The USB Modbus RTU interface relies on the USB
channel collecting data into 64 byte packets.
Document Number
For Internal Use Only: This document contains confidential, proprietary information of Omega Engineering/Newport Electronics,
The Document may not be copied or reproduced without the prior, written permission of Omega Engineering/Newport Electronics
Revision 1.0
Page 6 of 11
Advertisement
Table of Contents
