Woodward LS-5 v2 Series - Modbus Protocol

Please note that the bit sequence starts on the left with the least signi󰈡cant byte.
Example: The value -266 = FEF6 hex of type SIGNED16 is transmitted in two octets, 󰈡rst
F6 hex and then FE hex.
7.2.3 Modbus Protocol
Modbus is a serial communications protocol published by Modicon in 1979 for use with its
programmable logic controllers (PLCs). It has become a de facto standard
communications protocol in industry, and is now the most commonly available means of
connecting industrial electronic devices. The Woodward controller supports a Modbus RTU
Slave module. This means that a Master node needs to poll the controller slave node.
Modbus RTU can also be multi-dropped, or in other words, multiple Slave devices can
exist on one Modbus RTU network, assuming that the serial interface is a RS-485.
Detailed information about the Modbus protocol is available on the following website:
• ══▷ http://www.modbus.org/specs.php
There are also various tools available on the internet. We recommend using ModScan32
which is a Windows application designed to operate as a Modbus Master device for
accessing data points in a connected Modbus Slave device. It is designed primarily as a
testing device for veri󰈡cation of correct protocol operation in new or existing systems.
A trial version download is available from the following website:
•
══▷ http://www.win-tech.com/html/modscan32.htm
Address range
The controller Modbus Slave module distinguishes between visualization data and
con󰈡guration & remote control data. The di󰈠erent data is accessible over a split address
range and can be read via the "Read Holding Register" function.
Furthermore, controller parameters and remote control data can be written with the
"Preset Single Registers" function or "Preset Multiple Registers" (╚═▷ Fig. 169)
300 LS-5 v2 Series 37650
7 Interfaces And Protocols
7.2 Protocols
Released