CS Instruments DS 400 User Manual

DS 400 Side 5 of 36
2 Instructions
This manual is intended to provide instructions for the installation and use of the DS 400
MODBUS function. The DS 400 MODBUS function can let the MODBUS master device to
read out the online measurement values.
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
Communications, 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.
2.1 Definitions and abbreviations
CRC
Cyclic Redundancy Check
Used for error—checking in MODBUS RTU. See appendix
Modbus Master
A MODBUS device, which is able to access data in one or more connected
MODBUS slaves
Modbus Slave
A MODBUS device, which is able to respond to requests from a
single MODBUS master
Modbus Adresse
Throughout this document the following notation is used to
address
MODBUS RTU registers see chapter 8
Addressing: Holding Register 1009 is addressed in messages by 1008
PDU
MODBUS protocol data unit
ADU
MODBUS application data unit
MBAP
MODBUS application protocol
RS485
Refers to the 2—wire communication standard defined by
EIA/TIA-485. (Physical layer)
Ethernet
2.2 References
1. MODBUS over Serial Line Specification and Implementation Guide V1.02
modbus.org 2006 Dec 20
2. MODBUS APPLICATION PROTOCOL SPECIFICATION V1.1b modbus.org
2006 Dec 28
3. MODBUS Messaging on TCP/IP implementation Guide V1.0b
2006 Oct 34
4. DS 400 operation manual

CS Instruments DS 400 Specifications

General

Brand	CS Instruments
Model	DS 400
Category	Measuring Instruments
Language	English