Introduction; Definitions And Abbreviations; References - Siemens SITRANS F M MAGFLO series Operating Manual

Modbus RTU RS-485
1.

Introduction

1.1 Definitions and
Abbreviations

1.2 References

1. Introduction
This manual is intended to provide instructions for the installation and use of the Modbus RTU
add-on module, product code number FDK:085U0234, that can be used in the Siemens Flow
Instruments USM II family of transmitters, which presently includes MAG 6000 and MASS 6000.
The Modbus RTU module is effectively a gateway through which a Modbus RTU master device
can have controlled access to a number of Siemens Flow Instruments USM II signal converter
parameters.
This manual is not intended to be a complete tutorial on the Modbus RTU protocol, and it is
assumed the end user already has a general working knowledge of Modbus RTU communica-
tions, especially in respect of master station configuration and operation. However an overview
is included in the following section to explain some of the fundamental aspects of the protocol.
CRC
Modbus master
Modbus slave
Modbus address
RS-485
RTU
Reference 1
Reference 2
SFIDK.PS.023.D2.02
Cyclic Redundancy Check
Used for error-checking in Modbus RTU. See appendix
A Modbus device, which is able to access data in one or more
connected Modbus slaves
A Modbus device, which is able to respond to requests from a single
Modbus master
Throughout this document the following notation is used to address
Modbus RTU registers and coils:
1:123 Coil number 123 (addressed in messages by 122)
4:1234 Holding register 1234 (addressed in messages by 1233)
4:54321
Holding register 54321 (addressed in messages by 54320)
34567 The address of a coil/holding register as specified in a
message
Refers to the 2-wire communication standard defined by EIA/TIA-485.
(Physical layer)
Remote Terminal Unit = Standard Modbus transmission mode
Modbus over Serial Line
Specification & Implementation guide v. 1.0
modbus.org 12/02/02
Modbus Application Protocol Specification
v. 1.1
modbus.org 12/06/02
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