Bronkhorst Modbus slave interface User Manual

Download

Instruction manual

Modbus slave interface

for digital

Mass Flow / Pressure instruments

Doc. no.: 9.17.035U Date: 16-10- 2014

ATTENTION

Please read this instruction manual carefully before installing and operating the instrument.

Not following the guidelines could result in personal injury and/or damage to the equipment.

Head Office: Nijverheidsstraat 1a, NL-7261 AK Ruurlo, The Netherlands, Tel. +31 573 458800, info@bronkhorst.com

BRONKHORST®

Important information. Discarding this information could cause injuries to people or

Instrument or installation.

Disclaimer

Even though care has been taken in the preparation and publication of the contents of this manual, we do not assume legal or other liability for any inaccuracy, mistake, mis-statement or any other error of whatsoever nature contained herein. The material in this manual is for information purposes only, and is subject to change without notice.

Bronkhorst High-Tech B.V. July 2011

Symbols

damage to the

Helpful information. This information will facilitate the use of this instrument.

Additional info available on the internet or from your local sales representative.

Warranty

The products of Bronkhorst High-Tech B.V. are warranteed against defects in material and workmanship for a period of three years from the date of shipment, provided they are used in accordance with the ordering specifications and the instructions in this manual and that they are not subjected to abuse, physical damage or contamination. Products that do not operate properly during this period may be repaired or replaced at no charge. Repairs are normally warranted for one year or the balance of the original warranty, whichever is the longer.

See also paragraph 9 of the Conditions of sales:

http://www.bronkhorst.com/files/corporate_headquarters/sales_conditions/en_general_terms_of_sales.pdf

The warranty includes all initial and latent defects, random failures, and undeterminable internal causes.

It excludes failures and damage caused by the customer, such as contamination, improper electrical hook-up, physical shock etc.

Re-conditioning of products primarily returned for warranty service that is partly or wholly judged non-warranty may be charged for.

Bronkhorst High-Tech B.V. or affiliated company prepays outgoing freight charges when any party of the service is performed under warranty, unless otherwise agreed upon beforehand. However, if the product has been returned collect to our factory or service center, these costs are added to the repair invoice. Import and/or export charges, foreign shipping methods/carriers are paid for by the customer.

Page 2 Modbus interface 9.17.035

BRONKHORST®

Table of contents

1 GENERAL PRODUCT INFORMATION ................................................................................................. 4

1.1 INTRODUCTION ................................................................................................................................................ 4

1.2 MULTIBUS TYPES .............................................................................................................................................. 4

1.3 REFERENCES TO OTHER APPLICABLE DOCUMENTS ..................................................................................................... 5

1.3.1 Manuals and user guides: ........................................................................................................................... 5

1.3.2 Technical Drawings: .................................................................................................................................... 5

1.3.3 Software tooling: ........................................................................................................................................ 5

1.4 SHORT FORM START-UP ..................................................................................................................................... 6

2 FIELD BUS INSTALLATION ................................................................................................................. 7

2.1 GENERAL ........................................................................................................................................................ 7

2.2 MODBUS CONNECTOR ....................................................................................................................................... 7

2.2.1 Shielded RJ45 modular jack ......................................................................................................................... 7

2.2.2 Shielded a coded M12 connector ................................................................................................................ 8

2.3 MODBUS CABLES AND T-PARTS ........................................................................................................................... 9

2.3.1 RJ45 FTP cables ........................................................................................................................................... 9

2.3.2 M12 DeviceNet drop cables ...................................................................................................................... 10

2.4 TERMINATION ................................................................................................................................................11

2.4.1 Termination resistors ................................................................................................................................ 11

2.4.2 Biasing resistors ........................................................................................................................................ 11

3 CHANGING SLAVE ADDRESS AND BAUD RATE ................................................................................ 13

3.1 VIA ROTARY SWITCHES ON THE SIDE OF THE INSTRUMENT (IF PRESENT) ........................................................................13

3.2 VIA RS232: FLOWFIX ......................................................................................................................................13

3.3 VIA RS232: OTHER PROGRAMS ..........................................................................................................................14

3.4 VIA MICRO-SWITCH AND LED’S ON THE INSTRUMENT (IF PRESENT) .............................................................................14

3.4.1 Readout bus-address/MAC-ID and baud rate: .......................................................................................... 14

3.4.2 Change bus-address and baud rate: ......................................................................................................... 15

3.5 BY USER INTERFACE (IF PRESENT) ........................................................................................................................15

4 FUNCTIONAL DESCRIPTION ............................................................................................................ 16

4.1 GENERAL .......................................................................................................................................................16

4.2 IMPLEMENTATION CLASS ...................................................................................................................................16

4.3 RESPONSE TIME ..............................................................................................................................................17

4.4 SUPPORTED MODBUS FUNCTIONS .......................................................................................................................17

4.4.1 Read Holding Registers (03) ...................................................................................................................... 17

4.4.2 Write Single Register (06) ......................................................................................................................... 17

4.4.3 Write Multiple Registers (16) .................................................................................................................... 17

4.4.4 Diagnostics (08) ........................................................................................................................................ 18

4.4.5 Report Slave ID (17) .................................................................................................................................. 18

4.4.6 Available parameters ................................................................................................................................ 19

5 TROUBLESHOOTING ...................................................................................................................... 21

5.1 VISUAL DIAGNOSTICS .......................................................................................................................................21

5.2 STEP-BY-STEP .................................................................................................................................................21

5.3 BUS DIAGNOSTICS STRING .................................................................................................................................22

6 SERVICE ........................................................................................................................................ 23

Page 3 Modbus interface 9.17.035

BRONKHORST®

The implementation of the Modbus interface is based on the following standards:

[2] Modbus_over_serial_line_V1_02.pdf December 20, 2006

1 GENERAL PRODUCT INFORMATION

1.1 Introduction

This manual covers the Modbus interface, which offers a direct connection to Modbus for Bronkhorst meters / controllers. The Modbus instrument will behave as a slave. This means all communication (instructions / readout) will be performed by a master device on the same Modbus system. Mostly this will be a PC controlling a process. This manual explains how to install a Bronkhorst instrument to your Modbus system.

Bronkhorst: This includes Bronkhorst High-Tech B.V. , Bronkhorst Cori-Tech B.V. and

M+W Instruments GmbH.

More detailed information about Modbus can be found at www.modbus.org or any website of the (local) Modbus organisation of your country (when available).

digital mass-flow / pressure

[1] Modbus_Application_Protocol_V1_1b.pdf December 28, 2006

1.2 Multibus types

In 2000 Bronkhorst developed their first digital instruments according to the “multibus” principle. The basic pc-board on the instrument contained all of the general functions needed for measurement and control, including alarm, totalizing and diagnostic functions. It had analog I/O-signals and also an RS232 connection as a standard feature. In addition to this there is the possibility of integrating an interface board with DeviceNet™, Profibus-DP Modbus , FLOW-BUS or EtherCAT protocol. The first generation (MBC-I) was based on a 16 bit Fujitsu controller. It was superseded in 2003 by the Multibus type 2 (MBC-II). This version was also based on the 16 bit Fujitsu controller but it had several improvements to the MBC-I. One of them is the current steering of the valve. It reduced heat production and improved control characteristics. The latest version Multibus controller type 3 (MBC3) is introduced in 2011. It is build around a 72MHz 32 bit NXP ARM controller. It has AD and DA controllers on board which makes it possible to measure noise free and control valves without delays. The internal control loop runs 6 times faster compared to the MBC-II therefore control stability has improved significantly. It also has several improved functions like reverse voltage protection, inrush current limitation and overvoltage protection.

MBC3 instruments can be recognised by the “MBC3” placed on lower left side of the instrument label (see example).

Page 4 Modbus interface 9.17.035

BRONKHORST®

RS232 interface with

Bronkhorst High-Tech

Bronkhorst Cori-Tech

Bronkhorst High-Tech

Document 9.17.022

Document 9.17.050

Document 9.17.044

Document 9.17.023

Document 9.17.024

Document 9.17.025

Document 9.17.026

Document 9.17.035

Document 9.17.027

General instructions

Instrument type based

Operational instructions

Field bus specific

information

Document 9.17.031

M+W Instruments

Document 9.17.063

1.3 References to other applicable documents

Manuals and guides for digital instruments are modular. General instructions give information about the functioning and installation of instruments. Operational instructions explain the use of the digital instruments features and parameters. Field bus specific information explains the installation and use of the field bus installed on the instrument.

1.3.1 Manuals and user guides:

General instructions digital Mass Flow / Pressure

General instructions CORI-FLOW

General instructions mini CORI-FLOW

General instructions digital LIQUI-FLOW L30

Instruction manual MASS-STREAM D-6300

Operational instructions

for digital multibus

Mass Flow / Pressure

instruments

FLOW-BUS interface

PROFIBUS–DP interface

DeviceNet interface

Modbus interface

FLOW-BUS protocol

EtherCAT interface

1.3.2 Technical Drawings:

Hook-up diagram laboratory-style Modbus (document nr. 9.16.064) Hook-up diagram industrial style Modbus (document nr. 9.16.065) Hook-up diagram CORI-FLOW Modbus (document nr. 9.16.066) Hook-up diagram LIQUI-FLOW L30 digital Modbus (document nr. 9.16.075)

1.3.3 Software tooling:

FlowPlot FlowView FlowFix FlowDDE

Page 5 Modbus interface 9.17.035

All these documents can be found at:

http://www.bronkhorst.com/en/downloads

BRONKHORST®

START

Master

present

Set Slave address and

baud rate of instrument

Make sure your Modbus master has been installed to the system

Instruments will be delivered to customers on address 1 and with a baud rate of 19200 baud. switches on the instrument. Also y address and baud rate via the RS232 connectio instrument to apply the changes). Slave address and baud rate can also be changed using the button (if present) on the instrument.

Connect instrument

Physically connect the instrument to the Modbus network.

Test

Test communication between your master and the instrument(s)

Ready

1.4 Short form start-up

All necessary settings for this module are already performed at Bronkhorst. To follow next steps carefully is the quickest way to get this module operational in your own Modbus environment.

The easiest way to change the slave address is by use of the rotary

ou can use the FLOWFIX program to change Slave

n (it may be needed to restart the

Instruments with combined RS232 / RS485 signal lines and no user interface automatically detect the bus type at start-up.

Warning: this device uses a vendor specific pin layout on the RJ45 connector that differs from the Modbus recommended pin layout.

Page 6 Modbus interface 9.17.035

BRONKHORST®

1 8

The implementation of the Modbus interface is based on the following standards:

[2] Modbus_over_serial_line_V1_02.pdf December 20, 2006

Physical layer and communication protocol are detected automatically upon reception of messages.

protocol. After every power-up the communication detection mode is active.

RJ45 Connector

Receptable

Pin number

Description

2 FIELD BUS INSTALLATION

2.1 General

Modbus is a 3-wire, RS485-based field bus communication system for parameter value exchange. In this system each instrument / device is equipped with a micro-controller for its own dedicated task but also for exchanging parameter value information with other instruments / devices connected to the same Modbus system.

[1] Modbus_Application_Protocol_V1_1b.pdf December 28, 2006

These messages must be sent using the correct combination of physical layer and communication

Bronkhorst advices not to use more as 127 instruments in one bus system.

2.2 Modbus connector

2.2.1 Shielded RJ45 modular jack

Warning: this device uses a vendor specific pin layout on the RJ45 connector that differs from the Modbus recommended pin layout.

The shielded RJ45 modular jack connector (for non IP65 applications) has the following pin configuration:

1 +15…24Vdc supply

2 0V

3 Shield

4 0V

6 0V (Modbus common)

7 D0 Modbus (A/A')

8 D1 Modbus (B/ B')

+15…24Vdc supply

The maximum contact rating for RJ45 connectors is 1.5A.

For MASS-VIEW instrument see manual 9.17.051 for pin layout.

Page 7 Modbus interface 9.17.035

http://www.bronkhorst.com/en/downloads/instruction_manuals/

BRONKHORST®

M12 Connector

Male

Female

Description

4 2 3 5 1

A-coded

2.2.2 Shielded a coded M12 connector

The chassis M12 circular connector (for IP65 applications) has the following pin configuration:

1 Shield

3 0V

4 D1 Modbus (B/ B')

5 D0 Modbus (A/A')

+15…24Vdc supply

The maximum contact rating for M12 connectors is 4A.

Page 8 Modbus interface 9.17.035

BRONKHORST®

RJ45 shielded FTP CAT.5e cable

RJ45 shielded connectors

Shielded FTP cable

Power isolator

7.03.241 Modular Y adapter cable

CAT.5e cables are available with a wire of:

24AWG (wire diameter 0.205mm2, with a resistance of 86 Ohm/km).

2.3 Modbus Cables and T-parts

2.3.1 RJ45 FTP cables

For connecting instruments to Modbus you need shielded cables with at least 3 wires (for data only). Recommended are twisted wire cables for RS485-communications with 100 or 120 Ohm impedance. All Bronkhorst Modbus cables have also integrated power-supply wires. For the use in the EL-FLOW range (non IP-65) it is best to use Shielded (+Foiled) Twisted Pair patch-cables with RJ45 modular jack connectors (8-pins for data and power-supply connections).

26AWG (wire diameter 0.140mm2, with a resistance of 137 Ohm/km).

More information about cat.5e cables can be found at::

http://en.wikipedia.org/wiki/Category_5_cable

Page 9 Modbus interface 9.17.035

BRONKHORST®

M12 cable

M12 termination resistor

T-part

T-part wiring

2.3.2 M12 DeviceNet drop cables

For the use in for example the IN-FLOW range or CORI-FLOW range (IP-65 applications) it is best to use DeviceNet Drop cables assembled on both sides with male connector M12 – female connector M12 (5-pins for data and power-supply connections).

In case of powering instruments or transporting data over longer distances Bronkhorst offers also special RS485 Modbus data cable, with lower voltage-drop. Bronkhorst can advise you when to use this special cable, but for most cases the standard patch-cables will do well.

If more cables are used in one system, they have to be connected as a daisy-chain. This means that the total Modbus system has only one begin and one end. For connecting instruments to the bus, Bronkhorst offers special drop-cables which enable you to build a daisy chained network of Modbus modules.

Page 10 Modbus interface 9.17.035

BRONKHORST®

Bronkhorst advices the following resistor values for the following voltages.

Supply voltage

termination

Termination

resistors

Bias Pull-up

resistor

Bias Pull-down

resistor

+5V

121 Ohm

392 Ohm

+10V

121 Ohm

1210 Ohm

392 Ohm

+15V

121 Ohm

2210 Ohm

392 Ohm

+24V

121 Ohm

3480 Ohm

392 Ohm

2.4 Termination

For best quality of data transfer Modbus should be terminated correctly.

2.4.1 Termination resistors

A resistor is added in parallel with the receiver’s “A” and “B” lines in order to match the data line characteristic impedance specified by the cable manufacturer (120 Ω is a common value). This value describes the intrinsic impedance of the transmission line and is not a function of the line length. A terminating resistor of less than 90 Ω should not be used. Termination resistors should be placed only at the extreme ends of the data line (see Termination schematics resistors RT1 and RT2), and no more than two terminations should be placed in any system that does not use repeaters.

2.4.2 Biasing resistors

When an RS-485 network is in an idle state, all nodes are in listen (receive) mode. Under this condition there are no active drivers on the network. All drivers are tri-stated. Without anything driving the network, the state of the line is unknown. If the voltage level at the receiver’s A and B inputs is less than ±200 mV the logic level at the output of the receivers will be the value of the last bit received. In order to maintain the proper idle voltage state, bias resistors must be applied to force the data lines to the idle condition. Bias resistors are nothing more than a pull-up resistor (RB1) on the data D1 Modbus (B/B') line and a pull-down (to ground) on the data D0 Modbus (A/A') line. The “Termination schematic” illustrates the placement of bias resistors on a transceiver. The value of the bias resistors is dependent on termination and number of nodes in the system. The goal is to generate enough DC bias current in the network to maintain a minimum of 200 mV between the B and A data line. Consider the following example of bias resistor calculation.

Ideal situation:

Termination resistors: 120 Ohm Receiver resistance: omitted Bias supply voltage: 5Vdc Wanted situation is a minimum of 200mV between A and B lines and a common mode voltage of 2.5V.

Minimum current therefore: 200mV / 60 Ohm = 3.33mA Total maximum bias resistor value is (5V – 0.2V)/3.33mA = 1440 Ohm. The maximum value of each biasing resistor: 720 Ohm.

Situation with 127 nodes:

Termination resistors: 120 Ohm Receiver resistance: 12 KOhm Number of instruments: 127 Bias supply voltage: 5Vdc Wanted situation is a minimum of 200mV between A and B lines and a common mode voltage of 2.5V.

Total termination resistance: 120 // 120 // 12000* 127 = 120 // 120 // 94.5 = 36.7 Ohm Minimum current therefore: 200mV / 36.7 Ohm = 5.45mA Total maximum bias resistor value is (5V – 0.2V)/5.45mA = 880 Ohm. The maximum value of each biasing resistors: 440 Ohm. Lower values may be used. (Depending on maximum power consumption of the resistors)

Page 11 Modbus interface 9.17.035

BRONKHORST®

Termination schematic

RJ45

M12

703297

Begin terminator

703298

End terminator

703515

Begin terminator

703321

End terminator

+15…24Vdc

RB1 976 Ohm

RT1 121 Ohm

RB2 392 Ohm

Modbus system

D1 Modbus (B/B’)

D0 Modbus (A/A’)

RT2 121 Ohm

Begin termination (RED)

End termination (BLACK)

Bronkhorst offers special begin-termination connectors with the resistor network. This handles correct termination but also gives a defined voltage on the Modbus D1 and D0 line for even more reliability of the bus system. An end-terminator is also offered by Bronkhorst and handles correct termination ad the end of the bus.

Termination can be performed with special termination-connectors, offered by Bronkhorst.

Page 12 Modbus interface 9.17.035

BRONKHORST®

3 CHANGING SLAVE ADDRESS AND BAUD RATE

Default instruments will be delivered to customers on address 1 and with a baud rate of 19200 baud.

The slave address and baud rate of the Bronkhorst meter/controller Modbus slave can be changed to fit the instrument in your existing Modbus network. Standard baud rates for Modbus are 9600, 19200 (default) and 38400.

3.1 Via rotary switches on the side of the instrument (if present)

On the side of the instrument are rotary switches placed and a label with the explanation of the switches. Make sure to use a screwdriver which is suited for the switches.

The switches have the following function: ADDRESS (00 – 99)

With the ADDRESS switch, the instruments address can be set. The MSD is the high part of the decimal number and the LSD the low part. For instance address 25 means MSD on 2 and LSD on 5. The default switch position is 00. In this position the address is software programmable. The default software programmable address is 1.

During instrument initialisation, the address switches are read. If the switches specify a valid Modbus address, i.e. a value from 1 to 99, this value is used. If the specified address differs from the value stored in the instrument, the new address is saved in memory.

Adjusting the rotary switches during operation will not affect the actual address unless the instrument is re-powered and/or re-initialized.

When addressing by rotary switches is used, it's not possible to change the adress by RS-232 or by the microswitch.

3.2 Via RS232: FlowFix

‘Off-line’ via the RS232 communication port by means of a special tooling program, called FlowFix. FlowFix is a tool for multi-bus instruments that can be used for all field busses enabling the user to:

• Change slave address

• Read and optionally change the baud rate

• Make a service log file to be send to Bronkhorst in case of trouble

Connect your Bronkhorst meter / controller Modbus slave instrument to a free COM-port using the special cable with on one side a T-part (with male and female sub-D 9 connector) and on the other side a female sub-D 9 connector (part number 7.03.366). The single sub-D 9 connector should be connected to your COM-port and the female sub-D 9 of the T-part to the male sub-D 9 of the instrument. Standard cables are approx. 3 meters. Maximum length between PC and instrument allowed is approximately 10 meters.

Start-up FlowFix.exe and select the COM-port. The configuration screen will appear.

Enter the Slave address and Baud rate and press [OK]. Valid values for the slave address are between 1 and 247, valid values for the baud rate are 9600, 19200, 38400, 57600 and 115200. The changed values will be effective immediately after changing.

Page 13 Modbus interface 9.17.035

BRONKHORST®

More information about the RS232 protocol can be found in document 917027 Manual RS232 interface

http://www.bronkhorst.com/en/downloads/instruction_manuals/

LED indications for bus-address and baud rate

Green LED

Red LED

Time

Indication



Green



Red

amount of count flashes

(0...12)

0 ... 12 sec.

Maximum

tens in bus-address for instrument

Amount of count flashes

(0...9)

0 ... 9 sec.

Maximum

units in bus-address for instrument

baudrate setting for instrument

5 = 115200 Baud (MBC3 type only)

3.3 Via RS232: other programs

It is also possible to read and or change the slave address or baud rate by means of any program via RS232 using the COM-port of your PC on 38400 baud.

This document can be found at:

3.4 Via micro-switch and LED’s on the instrument (if present)

With the micro-switch on the instrument it is possible to change and readout the settings for slave address and baud rate. The LED’s will indicate the tens of the address with green flashes and the units with red flashes. For baud rateindication both LED’s will flash.

3.4.1 Readout bus-address/MAC-ID and baud rate:

Pressing the switch 3x briefly with intervals of max. 1 second in normal running / operation mode will trigger the instrument to “show” its bus-address/MAC-ID and baud rate.

For indication the bus-address/MAC-ID the green LED will flash the amount of tens and the red LED the amount of units in the number. For indication of baud rate setting, both LED’s will flash. The flashes are called “count-flashes” and have a pattern of 0.5 sec. on, 0.5 sec. off.

Off

amount of count flashes

(1...5)

Note: Value zero will be indicated by a period of 1 sec. off (0.5 sec. off + 0.5 sec. off).

Examples:

• For bus-address 35 and 9600 baud the green LED will flash 3 times, the red LED will flash 5 times and both

LED’s will flash 1 time.

• For bus-address 20 and 19200 baud the green LED will flash 2 times, the red LED will flash 0 times and both

LED’s will flash 2 times.

• For bus-address 3 and 38400 baud the green LED will flash 0 times, the red LED will flash 3 times and both

LED’s will flash 3 times.

Off

amount of count flashes

(1...5)

1 ... 5 sec.

Maximum

1 = 9600 Baud 2 = 19200 Baud 3 = 38400 Baud 4 = 57600 Baud (MBC3 type only)

Page 14 Modbus interface 9.17.035

BRONKHORST®

Procedure for changing bus-address and baud rate

Step

Action

Indication

time

handling

Start

Press the switch 5x briefly with intervals of max. 1 second in normal running/operation mode.

Set tens of bus-



Green LED flashes

0.5 sec off

time-out:

Press switch and count green flashes for tens of

Set units of bus-



red LED flashes

0.5 sec off

time-out:

Press switch and count red flashes for units of bus-

Set baud rate of

both 



red



0.5 sec off

time-out:

Press switch and count red and green flashes for

Before each action of flash-counting, the LED’s to be used for counting will flash in a high frequency.

off and the counting sequence will start.

3.4.2 Change bus-address and baud rate:

Pressing the switch 5x briefly with intervals of max. 1 second in normal running/operation mode. Within the time-out period of 60 seconds it is possible to start changing the bus-address/MAC-ID of the instrument. For certain field bus systems it is necessary to select the baud rate also. Other field bus systems only have one baud rate or the baud rate setting will adapt to the setting of the master automatically. In these cases baud rate selection is not needed and will be skipped.

address

Address

field bus

communication.

1 = 9600 Baud 2 = 19200 Baud 3 = 38400 Baud 4 = 57600 Baud

5 = 115200 Baud

0.1 sec on

0.1 sec off

count-flashes

start when switch

is pressed:

0.5 sec on,

0.1 sec on

0.1 sec off

count-flashes

start when switch

is pressed:

0.5 sec on

and

green

LED flashes

0.1 sec on

0.1 sec off

count-flashes

start when switch

is pressed:

0.5 sec on,

60 sec

bus-address. Release when wanted amount has been count.

Counts up to max. 12 and than starts at 0 again. When counting fails, keep switch pressed and restart counting for next attempt.

address. Release when wanted amount has been count.

Counts up to max. 9 and than starts at 0 again. When counting failed, keep switch pressed and restart counting for next attempt.

baud rate setting. Release when wanted amount has been count.

Counts up to max. 5 and than starts at 0 again. When counting failed, keep switch pressed and restart counting for next attempt.

Note: selection of 0 means: No change

Instrument returns to normal running / operation mode. Changes are valid when they are made within the time-out times.

Value zero will be indicated by a period of 1 sec. off (0.5 sec. off + 0.5 sec. off). When value zero is wanted, press switch shortly and release it again within 1 sec.

(Pattern: 0.1 sec on, 0.1 sec off). As soon as the switch is pressed-down, this LED (or both LED’s) will be

3.5 By user interface (if present)

See the manual of the instrument for a description of the user interface.

Page 15 Modbus interface 9.17.035

BRONKHORST®

The implementation of the Modbus interface is based on the following standards:

[2] Modbus_over_serial_line_V1_02.pdf December 20, 2006

General settings

parameter

options

remarks

addressing

address configurable from 1 to 247 (default 1)

broadcast support

yes

baud rate

9600

115200 Baud (MBC3 type only)

electrical interface

RS485 2W-cabling

data bits

RTU = 8, ASCII = 7

stop bits

The use of no parity requires 2 stop bits

MBCII / CORI-FLOW / M+W

parameter

options

remarks

parity

even

Not configurable

transmission mode

RTU

Not configurable

MBC3 / EL-FLOW Base

parameter

options

remarks

parity

even / odd / none

Configurable

transmission mode

RTU / ASCII

Configurable (MBC3) Auto detection (EL-FLOW Base)

MASS-VIEW

parameter

options

remarks

parity

even

Not configurable

transmission mode

RTU / ASCII

Configurable

4 FUNCTIONAL DESCRIPTION

4.1 General

The information found here is the basic information needed for the installation of a Modbus system.

[1] Modbus_Application_Protocol_V1_1b.pdf December 28, 2006

4.2 Implementation class

The physical and data link layer are implemented conforming to the "basic slave" implementation class as described in document [2] “MODBUS over Serial Line specification and implementation guide V1.02”. The following options have been implemented:

19200 (default) 38400 57600 Baud (MBC3 type only)

More detailed information about Modbus can be found at www.modbus.org or any website of the (local) Modbus organisation of your country (when available).

Page 16 Modbus interface 9.17.035

BRONKHORST®

Possible exception responses

Code

Name

Meaning

ILLEGAL DATA ADDRESS

in case of reading of non-existing address, or reading a part of a multi register parameter (float, long, etc)

ILLEGAL DATA VALUE

in case of reading less than 1 or more than 125 registers

SLAVE DEVICE FAILURE

in case of reading a write-only register

Warning: the maximum message size for the Read Holding Registers function is 100 bytes at 9600 baud

Possible exception responses

Code

Name

Meaning

ILLEGAL DATA ADDRESS

in case of writing to non-existing address, or writing to a part of a multi register parameter (float, long, etc)

SLAVE DEVICE FAILURE

in case of writing to read-only register

SLAVE DEVICE FAILURE

in case of writing illegal value to register

Possible exception responses

Code

Name

Meaning

ILLEGAL DATA ADDRESS

in case of writing to non-existing address, or writing to a part of a multi register parameter (float, long, etc)

ILLEGAL DATA VALUE

in case of reading less than 1 or more than 123 registers

SLAVE DEVICE FAILURE

in case of writing to read-only register

SLAVE DEVICE FAILURE

in case of writing illegal value to register

4.3 Response time

This slave device will respond on each valid request from the master within 100ms. This means that the response timeout setting of the master should be set to a value larger than or equal to 100ms.

4.4 Supported Modbus functions

This section describes the supported Modbus function codes. Refer to [1] for details.

4.4.1 Read Holding Registers (03)

(200 bytes at 19200 baud and 400 bytes at 38400 baud). When this size is exceeded, corrupted responses may be received.

4.4.2 Write Single Register (06)

4.4.3 Write Multiple Registers (16)

When one of the written registers raises an exception, the value written to all subsequent registers are discarded (ignored).

Page 17 Modbus interface 9.17.035

The following sub-functions are supported

Sub-function code (dec)

Name

Return Query Data

Clear Counters and Diagnostics Register

Return Bus Message Count

Return Bus Communication Error Count

Return Bus Exception Error Count

Return Slave Message Count

Return Slave No Response Count

Return Slave NAK Count (always 0)

Return Slave Busy Count (always 0)

Return Bus Character Overrun Count

Warning: the maximum message size for the Return Query Data sub function is 100 bytes at 9600 baud

responses may be received.

Possible exception responses

Code

Name

Meaning

ILLEGAL FUNCTION

of not-supported sub-function

ILLEGAL DATA VALUE

in case of an incorrect value for the data field

SLAVE DEVICE FAILURE

in case of writing illegal value to register

Possible exception responses

Code

Name

Meaning

SLAVE DEVICE FAILURE

in case of an internal error

4.4.4 Diagnostics (08)

(200 bytes at 19200 baud and 400 bytes at 38400 baud). When this size is exceeded, corrupted

BRONKHORST®

4.4.5 Report Slave ID (17)

The Slave ID field in the response is a string with the same contents as FlowDDE parameter 1 (ident number + version nr/serial nr). The Run Indicator Status field in this message will indicate ON when the device is in normal operating mode (FB_NORMAL).

Page 18 Modbus interface 9.17.035

BRONKHORST®

MODBUS REGISTERS

PARAMETER

Wink

Unsigned char

0x0000

0x0001

Value 14592

Initreset

Unsigned char

0x000A

0x000B

Valve output

Unsigned int

0x001F

0x0020

Range 0..32767

Measure

Unsigned int

0x0020

0x0021

Setpoint

Unsigned int

0x0021

0x0022

Setpoint slope

Unsigned int

0x0022

0x0023

Analog input

Unsigned int

0x0023

0x0024

Control mode

Unsigned char

0x0024

0x0025

Sensor type

Unsigned char

RW 

0x002E

0x002F

Capacity unit index

Unsigned char

RW 

0x002F

0x0030

Fluid number

Unsigned char

0x0030

0x0031

Alarm info

Unsigned char

0x0034

0x0035

Temperature

Unsigned int

0x0427

1063

0x0428

1064

See addr 0xA138

Alarm limit maximum

Unsigned int

0x0C21

3105

0x0C22

3106

Alarm limit minimum

Unsigned int

0x0C22

3106

0x0C23

3107

Alarm mode

Unsigned char

0x0C23

3107

0x0C24

3108

Alarm setpoint mode

Unsigned char

0x0C25

3109

0x0C26

3110

Alarm new setpoint

Unsigned int

0x0C26

3110

0x0C27

3111

Alarm delay

Unsigned char

0x0C27

3111

0x0C28

3112

Reset alarm enable

Unsigned char

0x0C29

3113

0x0C2A

3114

Counter value

Unsigned int

0x0D01

3329

0x0D02

3330

See addr 0xE808

Counter unit index

Unsigned char

0x0D02

3330

0x0D03

3331

Counter limit

Unsigned int

0x0D03

3331

0x0D04

3332

See addr 0xE818

Counter setpoint mode

Unsigned char

0x0D05

3333

0x0D06

3334

Counter new setpoint

Unsigned int

0x0D06

3334

0x0D07

3335

Counter mode

Unsigned char

0x0D08

3336

0x0D09

3337

Reset counter enable

Unsigned char

0x0D09

3337

0X0D0A

3338

Identification number

Unsigned char

RW 

0x0E2C

3628

0x0E2D

3629

Normal step c. resp.

Unsigned char

RW 

0x0E45

3653

0x0E46

3654

Stable situation c. resp.

Unsigned char

RW 

0x0E51

3665

0x0E52

3666

Open from zero c. resp.

Unsigned char

RW 

0x0E52

3666

0x0E53

3667

Calibration mode

Unsigned char

RW 

0x0E61

3681

0x0E62

3682

Monitor mode

Unsigned char

RW 

0x0E62

3682

0x0E63

3683

Reset

Unsigned char

0x0E68

3688

0x0E69

3689

Bridge potmeter

Unsigned char

RW 

0x0E85

3717

0x0E86

3718

Modbus slave address

Unsigned char

RW 

0x0FAA

4010

0x0FAB

4011

Polynomial constant A

Float

RW 

0x8128..0x8129

33064..33065

0x8129..0x812A

33065..33066

Polynomial constant B

Float

RW 

0x8130..0x8131

33072..33073

0x8131..0x8132

33073..33074

Polynomial constant C

Float

RW 

0x8138..0x8139

33080..33081

0x8139..0x81A

33081..33082

Polynomial constant D

Float

RW 

0x8140..0x8141

33088..33089

0x8141..0x8142

33089..33090

Sensor differentiator dn

Float

RW 

0x8158..0x8159

33112..33113

0x8159..0x815A

33113..33114

Sensor differentiator up

Float

RW 

0x8160..0x8161

33120..33121

0x8161..0x8162

33121..33122

Capacity

Float

RW 

0x8168..0x8169

33128..33129

0x8169..0x816A

33129..33130

Fluid name

String (10 bytes)

RW 

0x8188..0x818C

33160..33164

0x8189..0x818D

33161..33165

Capacity unit

String (7 bytes)

RW 

0x81F8..0x81FB

33272..33275

0x81F9..0x81FC

33273..33276

Fmeasure

Float R 0xA100..0xA101

41216..41217

0xA101..0xA102

41217..41218

FSetpoint

Float

0xA118..0xA119

41240..41241

0xA119..0xA11A

41241..41242

Temperature

Float R 0xA138..0xA139

41272..41273

0xA139..0xA13A

41273..41274

See addr 0x0427

Capacity 0%

Float

RW 

0xA1B0..0xA1B1

41392..41393

0xA1B1..0xA1B2

41393..41394

Counter value

Float

0xE808..0xE809

59400..59401

0xE809..0xE80A

59401..59402

See addr 0x0D01

Counter limit

Float

0xE818..0xE819

59416..59417

0xE819..0xE81A

59417..59418

See addr 0x0D03

Counter unit

String (4 bytes)

0xE838..0xE839

59448..59449

0xE839..0xE83A

59449..59450

Device type

String (6 bytes)

0xF108..0xF10A

61704..61706

0xF109..0xF10B

61705..61707

BHTModel number

String (14 bytes)

RW 

0xF110..0xF116

61712..61718

0xF111..0xF117

61713..61719

Serial number

String (16 bytes)

RW 

0xF118..0xF11F

61720..61727

0xF119..0xF120

61721..61728

Customer model

String (16 bytes)

RW 

0xF120..0xF127

61728..61735

0xF121..0xF128

61729..61736

Firmware version

String (5 bytes)

0xF128..0xF12A

61736..61738

0xF129..0xF12B

61737..61739

4.4.6 Available parameters

Modbus registers (in the data model) are numbered from 1 to 65536. In a Modbus PDU (Protocol Data Unit) these registers are addressed from 0 to 65535. This addressing model has been described in section 4.4 of [1].

The following table lists the most commonly used parameters.

PARAMETER NAME

TYPE

ACCESS

PDU ADDRESS REGISTER NUMBER

Hex Dec Hex Dec

REMARK

Page 19 Modbus interface 9.17.035

BRONKHORST®

Details and meaning can be found in document 9.17.023 Operation instructions digital instruments.

http://www.bronkhorst.com/en/downloads/instruction_manuals/

• Access indicates whether parameter can be Read and/or Written.

the full parameter range and resolution.

MODBUS REGISTERS

Usertag

String (13 bytes)

0xF130..0xF136

61744..61750

0xF131..0xF137

61745..61751

PID-Kp

Float

RW 

0xF2A8..0xF2A9

62120..62121

0xF2A9..0xF2AA

62121..62122

PID-Ti

Float

RW 

0xF2B0..0xF2B1

62128..62129

0xF2B1..0xF2B2

62129..62130

PID-Td

Float

RW 

0xF2B8..0xF2B9

62136..62137

0xF2B9..0xF2BA

62137..62138

Density actual

Float R 0xF478..0xF479

62584..62585

0xF479..0xF47A

62585..62586

Dynamic display factor

Float

RW 

0xF508..0xF509

62728..62729

0xF509..0xF50A

62729..62730

Static display factor

Float

RW 

0xF510..0xF511

62736..62737

0xF511..0xF512

62737..62738

Exponential smoothing

Float

RW 

0xF520..0xF521

62752..62753

0xF521..0xF522

62753..62754

Modbus baudrate

Long integer

RW 

0xFD48..0xFD49

64840..64841

0xFD49..0xFD4A

PARAMETER NAME

This document can be found at:

• When a byte parameter is read, the upper 8-bits of the Modbus register will be 0. When a byte

parameter is written, the upper 8-bits must be set to 0.

• Long integer parameters have a length of 4 bytes and are mapped on two consecutive Modbus

registers. The first register contains bit 32-16, the second register contains bit 15-0.

• Floating point parameters have a length of 4 bytes and are mapped on two consecutive Modbus

registers. Floats are in single precision IEEE format (1 sign bit, 8 bits exponent and 23 bits fraction). The first register contains bit 32-16, the second register contains bit 15-0.

• String parameters can have a length of maximal 16 bytes and can take up to 8 Modbus registers

where each register contains two characters (bytes). The upper byte of the first register contains the first character of the string. When writing strings, the write action should always start from the first register as a complete block (it is not possible to write a part of a string). If the string is shorter than the specified maximum length the string should be terminated with an 0.

• Parameters Temperature, Counter value and Counter limit can be found in the parameter table as

an unsigned integer variant and as a floating point variant. Only the floating point variant supports

PARAMETER

TYPE

ACCESS

PDU ADDRESS REGISTER NUMBER

Hex Dec Hex Dec

64841..64842

REMARK

Page 20 Modbus interface 9.17.035

BRONKHORST®

More information can be found in document 9.17.023 Operation instructions digital instruments.

http://www.bronkhorst.com/en/downloads/instruction_manuals/

START

Check Slave address and

baud rate

Check all Modbus settings at your master. Master and device settings must be the same, check baud rate and parity setting.

Check slave address and baud rate of device (slave).

Check cabling and

termination

Check cabling and bus termination of your Modbus system.

Check power supply

Check power supply. Instruments need +15Vdc or +24Vdc.

Ready

Check Master

Reset

Try to reset the instrument and/or restart your master.

Check diagnostics

Check the bus diagnostics string. See below.

5 TROUBLESHOOTING

5.1 Visual diagnostics

LED indications (if present) can be very useful in case of problems with the instrument.

The green LED is normally used for instrument status indication, like normal operation or special function mode. The red LED will burn continuously in case of a hardware failure. During normal operation, the red LED is switched on during frame reception or sending on the Modbus interface.

This document can be found at:

5.2 Step-by-step

Page 21 Modbus interface 9.17.035

BRONKHORST®

mAAAA

eBBBB

sCCCC

cDDDD

Diagnostics

=0000

No communication detected by slave, check RS485 network, especially D0 and D1 signals.

>0000

=0000

Slave detected valid Modbus messages for other addresses, make sure master uses correct slave address

=0000

>0000

=0000

Slave detected invalid messages on the bus, make sure master uses correct baud rate and parity settings

>0000

=0000

Slave detected both valid and invalid messages, make sure RS485

details.

=0000

>0000

=0000

>0000

Slave has received bytes faster than it could process, make sure

rate.

>0000

=0000

>0000

=0000

No problem detected by slave, make sure application timeout of master is set to a value larger than 100 ms

5.3 Bus diagnostics string

The bus diagnostics string can be found in the service report that can be created using FlowFix. The string is also available as parameter 202 in the Bronkhorst FlowDDE application.

The format of the string is "mAAAA eBBBB sCCCC cDDDD", where AAAA, BBBB, CCCC and DDDD are hexadecimal representations of 16-bit counters:

• AAAA = bus messages count (CPT1)

• BBBB = bus communication error count (CPT2)

• CCCC = slave message count (CPT4)

• DDDD = bus character overrun count (CPT8)

The following table may be helpful to find the source of communication problems on Modbus. In general, read out this string after trying to communicate between master and slave, without switching off the power in the meantime.

bus termination and polarization are used correctly and the maximum number of devices is not exceeded. See chapter 2 for

master uses correct baud rate. You may want to try a lower baud

Page 22 Modbus interface 9.17.035

BRONKHORST®







6 SERVICE

For current information on Bronkhorst and service addresses please visit our website:

Do you have any questions about our products? Our Sales Department will gladly assist you selecting the right product for your application. Contact sales by e-mail:

For after-sales questions, our Customer Service Department is available with help and guidance. To contact CSD by email:

No matter the time zone, our experts within the Support Group are available to answer your request immediately or ensure appropriate further action. Our experts can be reached at:

http://www.bronkhorst.com

sales@bronkhorst.com

support@bronkhorst.com

+31 573 45 88 39

Page 23 Modbus interface 9.17.035

Bronkhorst Modbus slave interface User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

1 GENERAL PRODUCT INFORMATION

1.1 Introduction

1.2 Multibus types

1.3 References to other applicable documents

1.3.1 Manuals and user guides:

1.3.2 Technical Drawings:

1.3.3 Software tooling:

1.4 Short form start-up

2 FIELD BUS INSTALLATION

2.1 General

2.2 Modbus connector

2.2.1 Shielded RJ45 modular jack

2.2.2 Shielded a coded M12 connector

2.3 Modbus Cables and T-parts

2.3.1 RJ45 FTP cables

2.3.2 M12 DeviceNet drop cables

2.4 Termination

2.4.1 Termination resistors

2.4.2 Biasing resistors

3 CHANGING SLAVE ADDRESS AND BAUD RATE

3.1 Via rotary switches on the side of the instrument (if present)

3.2 Via RS232: FlowFix

3.3 Via RS232: other programs

3.4 Via micro-switch and LED’s on the instrument (if present)

3.4.1 Readout bus-address/MAC-ID and baud rate:

3.4.2 Change bus-address and baud rate:

3.5 By user interface (if present)

4 FUNCTIONAL DESCRIPTION

4.1 General

4.2 Implementation class

4.3 Response time

4.4 Supported Modbus functions

4.4.1 Read Holding Registers (03)

4.4.2 Write Single Register (06)

4.4.3 Write Multiple Registers (16)

4.4.4 Diagnostics (08)

4.4.5 Report Slave ID (17)

4.4.6 Available parameters

5 TROUBLESHOOTING

5.1 Visual diagnostics

5.2 Step-by-step

5.3 Bus diagnostics string

6 SERVICE