Baumer ETTNM Manual do Utilizador descarregar pdf

The TEDM pressostat and the ETTNM thermostat have a serial RS485 port and use

the Modbus RTU communication protocol.

The Modbus protocol is a dialog protocol based on a hierarchical structure consisting

of a master and several slave devices. It supports reading the pressure level (TEDM)

or the temperature (ETTNM), as well as the status of each coil (open or closed).

Communication from master to 1 slave: the master sends a query and waits for a

response.

Communication from master to all slave devices: the master sends a message to all

slaves currently on the network, they execute the command in the message without

sending a reply.

Two slave devices cannot talk to each other.

Addressing

The devices on the bus are identiﬁed by addresses assigned by the user. The address

of each subscriber is not related to its physical location.

Master

Modbus Communication - Overview

Modbus communication - Principles

Communication from master to a single slave

The master queries the slave over the network and waits for a response from that

slave.

Master

Slave device A Slave device B Slave device C

Response

Query

Communication from master to all slaves

Communication from the master to all slave devices: the master sends a message

to all slaves currently on the network, they execute the command in the message

without sending a reply.

Master

Slave device A Slave device B Slave device C

Command

E.g.: slave device = TEDM / ETTNM ...

Slave device A Slave device B Slave device C

These addresses range from 1 to 247 and do not have to be assigned sequentially.

There cannot be two slave devices with the same address.

Factory default address TEDM / ETTNM: 246.

The query

It contains a function code telling the slave being queried what type of action is

required.

The data contains any additional information the slave may need to execute the func-

tion.

The checksum allows the slave to check the integrity of the query content.

The response

If an error occurs, the function code is changed to indicate that the reply is an excep-

tion response (MSB*=0: no error; MSB=1: error).

The data then includes a code (exception code) indicating the type of error.

Exception code:

01 Illegal function (function code error)

02 Error in the register address or coil address

08 Transmission error (after checking the CRC or the synchronization)

*MSB : Most Signiﬁcant Bit

Frame for query/response

Device #

of slave

Function code

+ error bit

Speciﬁc information

about the command

Checksum

1 byte 1 byte n bytes 2 bytes

Device #

of slave

Function code

+ error bit

Transmitted data Checksum

1 byte 1 byte n bytes 2 bytes

Response in case of an error:

Device #

of slave

Function code

+ error bit

Exception code Checksum

1 byte 1 byte 1 byte 2 bytes

Response:

Query:

Baumer Bourdon-Haenni S.A.S. · 125, rue de la Marre · B.P. 70214 · 41103 Vendôme Cedex · France

Tel. +33 (0)2 54 73 74 75 · Fax France +33 (0)2 54 73 74 74 · Fax Export +33 (0)2 54 73 74 73

[email protected] · www.baumer.com

320124 ind a 11/2012

INSTALLATION INSTRUCTIONS MODBUS TEDM - ETTNM

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Resumo do Conteúdo

Página 1 - TEDM - ETTNM

The TEDM pressostat and the ETTNM thermostat have a serial RS485 port and use the Modbus RTU communication protocol. The Modbus protocol is a dialog p

Página 2 - General format of a frame

The master instructs a slave. The function code tells the slave what type of action to carry out. For example: read the register, function code 03 hex

Página 3 - Transmission samples

Read Coil Status - function code 01 The master queries the TEDM/ETTNM about the coils’ status.The start address for reading the coils is ﬁxed and the

Página 4 - 320124 ind a 11/2012

320124 ind a 11/2012Baumer Bourdon-Haenni S.A.S. · 125, rue de la Marre · B.P. 70214 · 41103 Vendôme Cedex · FranceTel. +33 (0)2 54 73 74 75 · Fax Fra