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ZIEHL-ABEGG MODBUS RTU System, Technical Information, Page: 11 / 16

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ZIEHL-ABEGG MODBUS RTU System Technical Information Download Page 11

Initiierung der Anforderung

Master

MODBUS-Transaktion (ohne Fehler)

Slave

Empfang der Antwort

Ausführung der Aktion

Initiierung der Antwort

Funktionscode Anforderungsdaten

Funktionscode

Antwortdaten

Initiierung der Anforderung

Master

MODBUS-Transaktion (Antwort mit Fehlermeldung (Exception))

Slave

Empfang der Antwort

Fehlererkennung in Aktion

Initiierung der Fehlerantwort

Funktionscode Anforderungsdaten

Exception Funktionscode

Antwortdaten

Picture 13: MODBUS Communication Master - Slave

5.2

Communication parameters

5.2.1

Communication parameters for MODBUS member

Different parameters must be set for the MODBUS communication between the master and the 
slaves. These parameters and their settings are listed in the table below:

Address range (unless other-
wise noted)

Slave:
1 

–

 247

Master:
no special address

Broadcast

Yes

Transmission rate

19.200 Bd (default)

Parity/Stop

Even (standard) or none (CTE, PTE, UTE32)

Mode

RTU

Interface

RS485 2W 

–

 MODBUS

Data

8 data bits

Technical information 

MODBUS RTU System

 

–

 model series 

MODBUS transmission layer

R-TIL08_01-GB 1215

Part.-No. 

11/16

Summary of Contents for MODBUS RTU System

Page 1: ...System Technical description and installation Technical information MODBUS COMM Parameter MB Holding Register Address 3 Access RW NW Minimum value 0 Maximum value 65535 Bit 15 8 R TIL08_01 GB 1215 Part No english ...

Page 2: ...to MODBUS specification 9 4 5 2 Connections 4 pin Phoenix MSTB 2 5 9 4 5 3 Shielding 10 5 MODBUS transmission layer 10 5 1 Introduction 10 5 2 Communication parameters 11 5 2 1 Communication parameters for MODBUS member 11 5 2 2 Setting the slave address 12 6 Ziehl Abegg MODBUS RTU Description 13 6 1 Introduction 13 6 2 Data model and access options 13 6 3 Alternative slave addressing 13 7 Enclosur...

Page 3: ...e data transfer on the bus A master can send messages without an external request Slave devices are peripheral devices Typical slave devices are input output devices valves drives and transducers They receive no bus access authorisation i e they may only acknowledge received messages or send messages to the master when it requests them to In general Only one master may be active on a bus branch mo...

Page 4: ...and passive repeaters with max 63 fans End channel at the output of a passive repeater with max 63 fans Attention If the Ziehl Abegg Auto addressing is to be used no repeater may be used because the repeaters cannot pass on the auto addressing A special RS485 transceiver with 1 4 1 8 UL Unit Load and a transfer rate of 19 2 kBd for connecting up to 63 nodes is used to transfer the information The ...

Page 5: ...es If an RS232 RS485 converter gateway is used this must be electrically isolated 3 2 MODBUS structuring The following pictures show examples of an unsegmented picture 4 and a segmented picture 5 bus structure Master RT Fail Safe integrated Bus 1 1 2 3 62 63 RT 150 Picture 4 One segment with MODBUS master Bus 1 1 2 63 1 2 63 Bus 1 RT deactivated Bus 2 RT activated Bus 2 RT 150 Active Repeater RT 1...

Page 6: ...n be increased by using repeaters maximum 1 repeater in series Information If an external terminal e g type series AXG is used or devices e g ZTG8 L are supplied with voltage via the bus the maximum line length from the device up to its voltage supply must be limited depending on the used line and the current consumption min supply voltage 7 V at 12 V and 10 8 V at 24 V Maximum line length when co...

Page 7: ...f the bus line No more than 2 terminations may exist in lines without repeaters The following devices usually contain a connectable termination and bias resistors MODBUS master Repeater Since the MODBUS slave devices normally have no built in termination an external termination art no 380080 should preferably be connected to the end of the line When positioning the terminating resistors following ...

Page 8: ...us line is in an undefined state Bias resistors failsafe must be used to then obtain a defined voltage potential on the data lines in the quiescent state The bias resistors act for data line A D as pull up resistors normally against 5 V and for data line B D as pull down resistors against GND The following devices usually have built in bias resistors MODBUS master MB TCP Gateway Repeater For single ...

Page 9: ...Pair 2 on Pin 3 6 4 5 2 Connections 4 pin Phoenix MSTB 2 5 D D GND 24V Picture 10 Pin assignment Assignment table Ziehl Abegg Description MODBUS Description Description D D1 D1 B V1 voltage V1 V0 1 OFF State D D0 D0 A V0 voltage V0 V1 0 ON State GND Common optional circuit ground 24 VP optional 24V power supply When using telephone flex J Y St 2x2x0 6 we recommend the following allocation A D red B...

Page 10: ...quest request to all slaves Structure of the MODBUS frame The MODBUS application protocol defines a simple Protocol Data Unit PDU Adressfeld Funktionscode Daten CRC PDU für serielle MODBUS Übertragung MODBUS PDU Picture 12 General MODBUS frame The address field only contains the slave address in the serial MODBUS transmission The CRC value Cyclic Redundancy Check is calculated by the transmitting de...

Page 11: ...ortdaten Picture 13 MODBUS Communication Master Slave 5 2 Communication parameters 5 2 1 Communication parameters for MODBUS member Different parameters must be set for the MODBUS communication between the master and the slaves These parameters and their settings are listed in the table below Address range unless other wise noted Slave 1 247 Master no special address Broadcast Yes Transmission rat...

Page 12: ... item The detailed instructions which can be found in the appropriate operating instructions of the connected components must also be observed Attention partly limited address range However the address setting is easier when the terminating device has address setting switches or similar devices for address setting The set address is retained voltage failure Information In accordance with the MODBU...

Page 13: ...ing MODBUS functions for registers Read Input register function code 4 Read Holding register function code 3 Write Single register function code 6 Write Multiple registers function code 16 Les und schreibbare Daten z B Parameter Lesbare Daten z B Istwerte Holdings Registers Input Registers R W R MODBUS Zugriff Applikationsdaten Picture 14 data model The application data are arranged completely in ...

Page 14: ... Picture 15 Structure with autoaddressing Information Additional information please refer the relevant manuals of the devices 23 02 2011 v_modbus_net_autoadr_cbox eps vsd A G 247NW 3 3 V IRDA RXD IRDA TXD IRDA SD A D B D GND 5 V 4 63 1 BUS1 BUS2 2 BUS1 BUS2 3 BUS1 BUS2 GND ID1 A D B D 8 7 6 5 4 3 2 1 RJ45 RJ45 RJ45 Picture 16 Structure with connection box and RJ 45 cabling Technical information MO...

Page 15: ...nce per channel Too many transmission errors Transmission Errors CRC Errors The shield should always be contacted on shielded bus lines The shield is usually contacted on PE In systems with branches over several floors potential shifts of the PE connections may occur which cause a compensation current by the shield which can lead to communication disturbances To prevent this the shield can be disco...

Page 16: ...ntact our V STE support department for control systems ventilation technology Our worldwide contacts are available in our subsidiaries for deliveries outside of Germany www ziehl abegg com If you make returns for inspections or repairs we need certain information in order to facilitate focused trouble shooting and fast repair Please use our repair tickets for this It is provided to you after you h...

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