KROHNE OPTISONIC-V6 User Manual

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OPTISONIC V6

Modbus manual

KROHNE CT Products

Protocol description

set-up

Liability, disclaimer

KROHNE takes great care to make sure the information in this document is correct, accurate and as complete as deemed necessary. Despite this, KROHNE rejects any responsibility for the consequences of missing or incorrect information in this manual.

Responsibility for setting up and operating a Modbus communication link, as described in this manual, rests solely with parties involved in the implementation and operation of such a data communication link.

It is KROHNE policy to maintain and update this document as necessary, however this is not a controlled document. Owners of this document can not claim that KROHNE is responsible for replacing this version of this document in case an updated version becomes available.

Nothing from this document may be copied or reproduced without the written permission of KROHNE Altometer

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TABLE OF CONTENTS

1 INTRODUCTION ......................................................................................................................................3

2 PHYSICAL COMMUNICATION LAYER...................................................................................................4

3 SERIAL TRANSMISSION FORMAT ........................................................................................................5

3.1 ASCII mode ....................................................................................................................................5

3.2 RTU mode ......................................................................................................................................5

4 MODBUS MESSAGE FRAMING .............................................................................................................6

4.1 The Address Field (Device Address) .............................................................................................6

4.2 The Function Field .........................................................................................................................6

4.3 The Data Field................................................................................................................................6

4.4 Error Checking Methods ................................................................................................................7

4.4.1 Error check in ASCII mode transmission .............................................................................7

4.4.2 Error check in RTU mode transmission ...............................................................................7

4.5 Transmission gaps .........................................................................................................................7

4.5.1 ASCII mode..........................................................................................................................7

4.5.2 RTU mode............................................................................................................................7

4.6 Response time out .........................................................................................................................7

5 SUPPORTED FUNCTIONS .....................................................................................................................8

5.1 Function 01: READ COILS.............................................................................................................8

5.2 Function 02: READ DISCRETE INPUTS .......................................................................................8

5.3 Function 03: READ HOLDING REGISTERS .................................................................................9

5.4 Function 04: READ INPUT REGISTERS.......................................................................................9

5.5 Function 05: WRITE SINGLE COIL ...............................................................................................9

5.6 Function 06: WRITE SINGLE HOLDING REGISTER....................................................................9

5.7 Function 8: DIAGNOSTICS..........................................................................................................10

5.8 Function 15: WRITE MULTIPLE COILS ......................................................................................10

5.9 Function 16: WRITE MULTIPLE HOLDING REGISTERS...........................................................10

5.10 Exception Responses ..................................................................................................................11

6 HANDLING OF LARGE DATA TYPES ..................................................................................................12

6.1 Integer (16 bit), Transmit Sequence ............................................................................................12

6.2 Long integer (32 bit), Transmit Sequence....................................................................................13

6.3 Single precision floating-point (32 bit), Transmit Sequence ........................................................13

6.4 Double precision floating-point (64 bit), Transmit Sequence .......................................................13

6.5 Long long (64 bit integer), Transmit Sequence............................................................................14

6.6 Maximum number requested items..............................................................................................14

7 DEFAULT SETTINGS ............................................................................................................................15

8 MODBUS REGISTER MAPPING...........................................................................................................16

8.1 Input Registers (read-only): Integer (16-bit); address range 3000-3499 .....................................16

8.2 Holding Registers (read/write): Integer (16-bit); address range 3500-3999 ................................17

8.3 Input Registers (read-only): Long integer (32-bit); address range 5000-5499 ............................17

8.4 Holding Registers (read/write): Long integer (32-bit), address range 5500-5999 .......................20

8.5 Input Registers (read-only): Double (64-bit floating-point), address range 6000-6499 ...............21

8.6 Holding Registers (read/write): Double (64-bit floating-point), address range 6500-6999 ..........21

8.7 Input Registers (read-only): Float (32-bit floating-point), address range 7000-7499...................22

8.8 Holding Registers (read/write): Float (32-bit) floating-point, address range 7500-7999..............25

8.9 Input Registers (read-only): Long long (64-bit integer), address range 8000-8499.....................28

8.10 Holding Registers (read/write): Long long (64-bit integer), address range 8500-8999................29

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1 INTRODUCTION

Scope

This manual describes how to use the Modbus protocol with the OPTISONIC V6 gas flow meter.

Introduction to Modbus

Modbus communication is based on the master-slave principle. Only the master can initiate transactions (requests), and only the addressed device (slave) responds. The master can also send a broadcast message (“message to all”); none of the slaves will respond to such a message.

The OPTISONIC V6 flow meter always acts as a Modbus compatible slave when communicating with host systems. Slaves are identified by means of a “device address”. Check the documentation to find the preset device address of your OPTISONIC V6 flow meter. In case necessary, the address can be reprogrammed. Contact the manufacturer for information about the procedures and tools that are needed for reprogramming the device address.

The Modbus protocol defines a message structure that Modbus enabled controllers will recognise and use, regardless of the type of network over which they communicate. It describes:

• the process a controller uses to request access to other devices,

• how to respond to requests from the other devices, and

• how errors will be detected and reported.

The Modbus request consists of:

• an address,

• a function code defining the requested action,

• data (if necessary for the requested function), and

• an error check for testing the integrity of the message.

The slave’s response contains:

• the slave address,

• data conform the request type, and

• an error check.

If the data integrity test fails, no response is sent back. If a request cannot be processed an exception message is returned.

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2 PHYSICAL COMMUNICATION LAYER

The Modbus over serial line protocol is a master-slave protocol. The physical layer can be half-duplex or fullduplex.

In case of the OPTISONIC V6 the physical layer is a half-duplex (two-wire) connection according to RS 485 specifications.

The end of a RS485 line has to be terminated by means of a resistor. This terminating resistor is included in the line driving circuit in the OPTISONIC V6.

Multiple OPTISONIC V6 meters may be connected to the same RS 485 line. In this case only the terminating resistor in the OPTISONIC V6 at the end of the line should be connected. The terminating resistors in the other OPTISONIC V6 meters on the line should be disconnected by means of the switch on the RS 485 driver printed circuit board. Default this switch is set to connect the line terminating resistor.

Because of the half-duplex operation, the RS 485 communication circuit in the OPTISONIC V6 is normally always in data receiving mode. Only in case it is requested to send it will automatically switch to data transmit mode for the time needed.

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3 SERIAL TRANSMISSION FORMAT

Two transmission modes are defined for a Modbus data communication link:

• Modbus ASCII

• Modbus RTU.

Both transmission modes are supported, the user can select the desired mode along with the serial communication parameters (baud rate, parity).

The default configuration of the OPTISONIC V6 is Modbus RTU communication mode with “standard” Modbus settings.

Check chapter 7 for a list of programmable parameters and the default settings of these parameters. Except for the device addresses all these parameters must be the same for all controllers in the network.

3.1 ASCII mode

In the Modbus message each byte of data is coded as 2 ASCII characters; one to represent the upper 4 bits and another to represent the lower 4 bits. Each group of 4 bits is represented by a hexadecimal number, transmitted as an ASCII character from the range 0-9, A-F.

Standard serial communication parameters: Start bits: 1 Data bits: 7 Parity: odd/even/none Stop bits: 1 stop bit if parity is used, or

2 stop bits if no parity is used.

Error check field: Longitudinal Redundancy Check (LRC).

An advantage of ASCII mode is that it allows for a time interval up to 1 second between characters without causing a timeout. A disadvantage of ASCII mode is the larger message length.

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3.2 RTU mode

Each byte of data is represented in the message by an equivalent number of bits (8).

The number of bits transmitted in the process of communicating one byte of information is sometimes also referred to as a “character”. Note that this is not the same as an ASCII character.

Default serial communication parameters: Baud rate: 19200 Data bits: 8 Parity: even Stop bits: 1 Error check field: Cyclic Redundancy Check (CRC).

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4 MODBUS MESSAGE FRAMING

ASCII mode

In ASCII mode a message starts with a colon character (:) and ends with a carriage return-linefeed.

Intervals up to one second can elapse between characters within the message. If the interval is longer, a timeout error occurs and the message is rejected.

RTU mode

In RTU mode a message starts with a silent time interval equivalent to at least 3.5 characters. The entire message frame must be transmitted as a continuous stream. If a silent interval of more than 3.5 character times occurs before completion of the frame, the receiving device flushes the incoming message and assumes that the next byte will be the address field for the new message.

Example of a typical message frame:

Mode START ADDRESS FUNCTION DATA CHECKSUM END ASCII Mode

RTU

Mode

‘:’ 2 characters 2 characters

3.5

characters

silent interval

8 bits 8 bits N*8 bits

N*2

characters

LRC

2 characters

CRC

16 bits

CR-LF

3.5 character silent interval

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4.1 The Address Field (Device Address)

The address field of a message frame contains: ASCII mode: 2 characters RTU mode: 8 bits

Valid slave addresses are 1 to 247. Address 0 is used for a broadcast to address all slaves.

4.2 The Function Field

The function field of a message frame contains: ASCII mode: 2 characters RTU mode: 8 bits

Valid function codes lie in a range of 1 to 127.

The function code tells the slave which kind of action to perform.

The supported functions are listed in chapter 5.

A slave response always contains the function code of the request. If a function is not applicable, the slave sends an exception response. An exception is indicated by a returned function code with bit 8 (most significant bit) set.

4.3 The Data Field

The data field contains 8 bit values (bytes) in the range of 0 to FF hexadecimal.

In ASCII mode each 8 bit value is represented by 2 ASCII characters.

The data field of messages contains information which both master and slave use to perform an action. This includes the register address, quantity of registers, and the necessary data.

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4.4 Error Checking Methods

Two error checking methods are defined for the Modbus protocol:

• Optional: an additional bit (parity bit) is appended to each character (or byte) for detecting errors

during the transmission of individual characters (or bytes)

• Obligatory: two bytes (or characters) are appended to the message for detecting errors during the

transmission of the message

As an even number of bit errors in one character (or byte) will not be detected using a parity bit, the second method is used to check the contents of the entire message.

Both character check and message check are generated in the transmitting device and appended to the message before transmission. The slave checks each character and the entire message frame during receipt.

The contents of the error checking field for the entire message depend on the transmission mode.

4.4.1 Error check in ASCII mode transmission

For detecting errors in the entire message the error-checking field contains two ASCII characters. The error check characters are the result of a Longitudinal Redundancy Check (LRC) calculation. This is performed on the message contents with exception of the beginning colon, the carriage return and line feed characters. The LRC characters are appended to the message as the last field preceding the CR-LF characters.

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4.4.2 Error check in RTU mode transmission

For detecting errors in the entire message the error-checking field contains a 16-bit value implemented as two bytes. The error check value is the result of a Cyclic Redundancy Check (CRC) calculation performed on the message contents. The CRC field is appended to the message as the last field.

4.5 Transmission gaps

Gaps that exceed a specific value during the transmission of a message will be qualified as a transmission error.

4.5.1 ASCII mode

In ASCII mode the maximum time between 2 characters is one second. If a longer interval occurs, the message will be ignored and the search for a starting character (colon) is resumed.

4.5.2 RTU mode

In RTU mode the entire message frame must be transmitted as a continuous stream. If a silent interval of more than 3.5 character times occurs before completion of the frame, the receiving device ignores the message and assumes the next byte will be the device-address field of a new message.

4.6 Response time out

The master device has a predetermined time-out interval before aborting a transaction.

This interval shall be set long enough for any slave to respond normally.

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5 SUPPORTED FUNCTIONS

A number of functions is available to perform operations on variables in the slave.

An operation can be a “read” operation to obtain the value of a variable or a “write” operation to assign a value to a variable. Variables are identified by means of their register number (address).

Typically in a Modbus slave, data can be stored in multiple areas that can be seen as different memories:

• Discrete Inputs: data from logical (also called binary, Boolean, or ON/OFF) inputs. By nature the data

in this area is “read-only”: the master has only access to read this data.

• Coils: logical (also called binary, Boolean, or ON/OFF) outputs. The master device may read the

current state of an output, but may also set or change the state of an output.

• Input Registers: data, for example originating from electrical inputs of the slave or results from

calculations in the slave, can be stored in “input registers”. By nature the data in this area is “readonly”: the master has only access to read this data.

• Holding Registers: the master has access to this area to read the data but as well to set or change the

value of data (write).

As these register groups are located in apparently different memories, the addresses may overlap: for example, an input register having address 100 can exist and at the same time a holding register having address 100. These are not the same: which one will be selected for an operation is implied from the function code, referring to an input register or to a holding register, for example.

The OPTISONIC V6 does not use Discrete Inputs or Coils, but only Input Registers and Holding Registers.

Variables are grouped according to data type and dependant of being input registers (read-only data) or being holding registers (read/write data). An address range is assigned to each variable type, subdivided in input registers (read-only) and holding registers (read/write).

The OPTISONIC V6’s address ranges of Input Registers and Holding Registers do not overlap. Accessing a specific register address is therefore unambiguous. The functions “read register” and “read input” could both be used to effectively access the same register/address. However, in this application, functions shall still be used consistent with the type of memory they are intended to be used for.

In the master and the slave register addresses are referenced (counted) starting from 1. However, the address range used in the message during in the transmission starts from 0. As an example, when referencing address 4001, the address actually present in the message will be 4000.

On an application level the user will not notice this, as during the coding and decoding of the message this offset of 1 will be taken into account. However, when the message – as it is transmitted – is analyzed and checked one has to be aware of this offset.

When functions which do not support broadcast requests, are accessed with a broadcast address, the request will be ignored.

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5.1 Function 01: READ COILS

Function 01 reads the status of 1 to 2000 contiguous logical (Boolean or ON/OFF) variables.

This function is not used, as in this application Boolean (or logical) variables are not used as individual entities. Boolean variables are represented by means of specific bits packed in 32 bit data word (type “Long”).

5.2 Function 02: READ DISCRETE INPUTS

Function 02 reads the status of 1 to 2000 contiguous logical (Boolean or ON/OFF) variables.

This function is not used, as in this application Boolean (or logical) variables are not used as individual entities. Boolean or logical variables are represented by means of specific bits packed in 32 bit data word (type “Long”).

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5.3 Function 03: READ HOLDING REGISTERS

Function 03 reads the contents of 1 to 125 contiguous holding registers in the slave.

The maximum number of registers at each request is limited to 125 16-bit registers: 125 integers, 62 long integers, 62 floats, 31 doubles or 31 long longs.

Request

The request message specifies the starting register and the quantity of registers to be read. Registers are addressed starting from zero. Registers 1-16 are addressed as 0-15.

Example

A request to read from slave device 17, registers 40108-40110 (decimal), or starting from 9CAC (hex):

Header

Slave

Address

11(h)

Function

03(h)

Starting address Number of data items

9C(h)

Low

AB(h)

00(h)

Low

03(h)

Error check

Trailer

Response:

Slave

address

11(h)

Function

03(h)

Byte

count

06(h)

(Reg.

40108

Hi)

02(h)

(Reg.

40108

Low)

2B(h)

(Reg.

40109

Hi)

00(h)

Data Header

(Reg.

40109

Low) 00(h)

(Reg.

40110

Hi)

00(h)

(Reg.

40110

Low)

64(h)

Error

check

Trailer

For each register the first byte contains the high order byte, the second the low order byte.

The contents of register 40108 are shown as the two byte values of 02 2B hex (555 decimal). The contents of register 40109 is 00 00 hex (0 decimal) and of register 40110 is 00 64 hex (100 decimal).

If the request is not applicable, an exception response will be sent. See chapter 5.10 for exception

responses.

5.4 Function 04: READ INPUT REGISTERS

Function 04 performs a “read” operation, similar to function 03. The difference is that function 04 addresses input registers (which are “read-only”), whereas function 03 addresses holding registers (which are “read/write”).

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5.5 Function 05: WRITE SINGLE COIL

Function 05 writes the status of a logical (Boolean or ON/OFF) variable.

This function is not used, as in this application Boolean variables are not used as individual entities. Boolean variables are represented by means of specific bits packed in 32 bit data word (type “Long”).

5.6 Function 06: WRITE SINGLE HOLDING REGISTER

Function 06 presets a value into a single holding register.

When the address is a broadcast, all slaves will process the request.

Request

The request specifies the register reference to be written. Registers are addressed starting from zero.

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Registers 1-16 are addressed as 0-15. The value to be written is specified in the data field, which is a 16-bit value.

Example

Request for slave 17 to preset register 40002 (decimal), 9C42 (hex) to 00 03 (hex).

Header

Slave

Address

11(h)

Function

06(h)

9C(h)

Low

41(h)

00(h)

Low

03(h)

Error Check

Trailer

Response

The response message is an echo of the request, returned after the register contents has been written.

Header

Slave

Address

11(h)

Function

06(h)

9C(h)

Low

41(h)

00(h)

Low

03(h)

Error Check

Trailer

If the request is not applicable, an exception response will be sent. See chapter 5.10 for exception responses.

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5.7 Function 8: DIAGNOSTICS

Function 8 provides a test for checking the communication system between the master and the slave.

Request

The function uses a two-byte sub-function field in the request to define the test to be performed:

Header

Slave address

11(h)

Function

08(h)

Sub-function

00 00(h)

Data Hi+Lo

A1B8 (h)

Error check

Trailer

All sub-functions are supported.

5.8 Function 15: WRITE MULTIPLE COILS

Function 15 writes the status of 1 to 2000 contiguous logical (Boolean or ON/OFF) variables.

5.9 Function 16: WRITE MULTIPLE HOLDING REGISTERS

Function 16 writes the contents of 1 to 123 contiguous holding registers in the slave.

When the address is a broadcast, the function pre-sets the same register references in all attached slaves.

Request

The request message specifies the register references to be pre-set. Registers are addressed starting at zero (register 1 is addressed as 0).

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Example

An example of a request for slave device 17 to pre-set two registers starting at 40002 (decimal), 9C42 (hexadecimal) to 00 0A end 01 02 hex:

Header

Slave

Address

11(h)

Func-

tion

10(h)

Starting address

9C(h)

Low

41(h)

Quantity

Registers

00(h)

Byte

counts

Low

02(h) 04(h)

00(h)

Low

0A(h)

Data

01(h)

Low

02(h)

Error

check

Trailer

Response

The normal response returns the slave address, the function code, starting address, and quantity of registers pre-set:

Header

Slave

Address

11(h)

Function

10(h)

9C(h)

Starting

Address

Low

41(h)

00(h)

Quantity

Of points

Low

02(h)

Error

check

Trailer

If the request is not applicable, an exception response will be sent. See chapter 5.10 for exception responses.

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5.10 Exception Responses

Except for broadcast messages, a master device expects a normal response, when it sends a request to a slave device. One of the four possible events can occur upon the master device’s request:

• If the slave device receives the request without a communication error and can handle the request

normally, it returns a normal response.

• If the slave does not receive the request due to a communication error, no response is returned. The

master program will eventually process a timeout condition for the request.

• If the slave receives the request, but detects a communication error (parity, CRC, LRC), no response

is returned. The master program will eventually process a timeout condition for the request.

• If the slave receives the request without a communication error, but cannot handle it, the slave will

return an exception response informing the master of the nature of the error.

The exception response message has two fields that differentiate it from a normal response.

Function Code Field

In a normal response the slave echoes the function code of the original request in the function code field of the response. In an exception response the slave sets the most significant bit of the function code to 1.

The master recognises the exception response by means of this bit and can examine the data field for the exception code.

Data field

In an exception response the slave returns an exception code in the data field. By means of this exception code the slave reports a reason for not being able to respond normally.

The exception response message:

Header Slave address Function Exception code Error check Trailer

Exception codes

Code Name Meaning

01 Illegal function The function code in the request is not an allowable action for the slave. 02 Illegal data address The data address received in the request is not an allowable address for the

slave.

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6 HANDLING OF LARGE DATA TYPES

The standard Modbus specification does not explain how data types larger than 16 bits should be handled. As larger data types are stored in a multiple of 16 bit registers, such data can be accessed by means of “read” or “write” operation on a series of consecutive 16 bit registers.

Function 03 (read multiple holding registers), function 04 (read input registers), function 06 (write single holding register), and function 16 (write multiple holding registers) are used to read or modify these data types.

Taking the data type into account, the addressing can be “optimized” accordingly, this is implemented in an addressing mode not compatible with the original Modicon concept:

• In the original “Modicon compatible mode” one address is assigned and counted for each 16 bit

register. To hold for example a 64-bit integer value, 4 addresses would be occupied. Therefore, in order to address the next variable of this type, the address has to be incremented by 4.

• In “not-Modicon compatible mode” addresses are incremented by 1 for each next variable. For

example, in order to read or write the next 64-bit variable, the register area to be read will automatically be shifted by 4 16 bit registers.

The OPTISONIC V6 is by default configured for Modicon compatible addressing.

The supported data types are:

• Integer (16 bit)

• Long integer (32 bit)

• Float (single precision floating-point, 32 bit)

• Double (double precision floating-point, 64 bit)

• Long long (64-bit Integer)

The register ranges for each data type:

Data type Address range

Integer (16 bit) 3000..3999 1 1

Long integer (32 bit) 5000..5999 2 1

Double (64 bit) 6000..6999 4 1

Float (32 bit) 7000..7999 2 1

Long long (64 bit) 8000..8999 4 1

Note that in Modicon compatible mode each data type larger than 16 bits should be addressed as an

appropriate number of 16-bit registers. For instance the first float is located at address 7000/7001; the next float is located at address 7002/7003.

A double would be accessed by four 16-bit registers, so the first double 6000/6001/6002/6003 and the next double 6004/6005/6006/6007.

The data in the chapter 8, “MODBUS REGISTER MAPPING”, is printed both as it should be addressed in

Modicon compatible and as well as in not-Modicon compatible mode.

Number of registers to request for each data type

Modicon compatible Not Modicon compatible

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6.1 Integer (16 bit), Transmit Sequence Integers are transmitted and stored with the most significant part first.

Example

Integer value 1790 decimal (6FE hexadecimal) is transmitted as:

First transmitted byte in data field Second transmitted byte in data field

06 FE

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6.2 Long integer (32 bit), Transmit Sequence

Example

Long integer value 305419896 (12345678 hexadecimal).

Long integers could be transmitted in two possible ways. The transmit order in both modes:

Normal mode

Reversed mode

(1)

12h

(3)

56h

(2)

34h

(4)

78h

(3)

56h

(1)

12h

(4)

78h

(2)

34h

6.3 Single precision floating-point (32 bit), Transmit Sequence

Single precision floating-point numbers are stored in 32-bit registers, represented using the IEEE 754

encoding. In IEEE 754-2008 the 32-bit base 2 format is officially referred to as binary32. It was called single

in IEEE 754-1985.

The IEEE 754 standard specifies a binary32 as having:

• Sign bit: 1 bit

• Exponent width: 8 bits

• Significand (also known as mantissa) precision: 24 (23 explicitly stored)

The true significand (mantissa) includes an implicit leading bit with value 1 unless the exponent is stored with all zeros. Thus only 23 bits of the significand (mantissa) appear in the memory format but the total precision is 24 bits (equivalent to log10(224) ≈ 7.225 decimal digits). The bits are laid out as follows:

Sign + (Biased) Exponent Exponent + Mantissa 3 (high) Mantissa 2 Mantissa 1 (low)

SEEE EEEE E MMM MMMM MMMM MMMM MMMM MMMM

The single precision binary floating-point exponent is encoded using an offset binary representation, with the zero offset being 127; also known as exponent bias in the IEEE 754 standard.

Example:

The float number 4.125977 will give the IEEE 754representation.

Sign Exponent Mantissa

0 1000 0001 (1) 000 0100 0000 1000 0000 0000

A positive sign A biased exponent of 129 (81 hexadecimal) is exponent 2. Mantissa = 4 + 1/8 + 1/1024. Note that the first bit is not stored!

Floats could be transmitted in two ways. The transmit order in both modes:

IEEE 754

Normal mode

Reversed mode

(1)

40h

(1)

40h

(3)

08h

(2)

84h

(2)

84h

(4)

00h

(3)

08h

(3)

08h

(1)

40h

(4)

00h

(4)

00h

(2)

84h

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6.4 Double precision floating-point (64 bit), Transmit Sequence

Double precision floating-point numbers are stored in 64-bit registers, represented using the IEEE 754

encoding. In IEEE 754-2008 the 64-bit base 2 format is officially referred to as binary64. It was called double in IEEE 754-1985.

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The IEEE 754 standard specifies a binary64 as having:

• Sign bit: 1 bit

• Exponent width: 11 bits

• Significand (also known as mantissa) precision: 53 (52 explicitly stored)

The true significand (mantissa) includes an implicit leading bit with value 1 unless the exponent is stored with all zeros. Thus only 52 bits of the significand (mantissa) appear in the memory format but the total precision is 53 bits (equivalent to log10(2

Sign + (Biased) Exponent Exponent + Mantissa Mantissa 6 Mantissa 5

SEEE EEEE EEEE MMMM MMMM MMMM MMMM MMMM

Mantissa 4 Mantissa 3 Mantissa 2 Mantissa 1

MMMM MMMM MMMM MMMM MMMM MMMM MMMM MMMM

) ≈ 16 decimal digits). The bits are laid out as follows:

Example

The double number 4.125000001862645 will give the IEEE representation:

Sign Exponent Mantissa

0 100 0000 0001 (1)0000 1000 0000 0000 0000 0000 0000 0010 0000 0000 0000 0000 0000

A positive sign A biased exponent of 1025 (401 hexadecimal) is exp. 2 Mantissa = 4 + 1/8 + 1/536870912. Note that the first bit is not stored!

Doubles could be transmitted in two ways. The transmit order in both modes:

IEEE 754

Normal mode

Reversed mode

(1)

40h

(1)

40h

(3)

80h

(2)

10h

(2)

10h

(4)

00h

(3)

80h

(3)

80h

(1)

40h

(4)

00h

(4)

00h

(2)

10h

(5)

00h

(5)

00h

(7)

00h

(6)

20h

(6)

20h

(8)

00h

(7)

00h

(7)

00h

(5)

00h

(8)

00h

(8)

00h

(6)

20h

KROHNE CT Products

6.5 Long long (64 bit integer), Transmit Sequence

Example

64 bit integer value 4.616.330.355.545.210.880 (= 4010 8000 0020 0000 hexadecimal).

64 bit integers could be transmitted in two ways. The transmit order in both modes:

Normal mode

Reversed mode

(1)

40h

(3)

80h

(2)

10h

(4)

00h

(3)

80h

(1)

40h

(4)

00h

(2)

10h

(5)

00h

(7)

00h

(6)

20h

(8)

00h

(7)

00h

(5)

00h

(8)

00h

(6)

20h

6.6 Maximum number requested items

The maximum amount of data that can be sent in a single response limits the amount of items that can be requested in a single query. The table below shows the maximum number of items per data type:

Data type Number of items

Boolean 2000 Integer (16 bit) 125 Long integer (32 bit) 62 Float (32 bit floating point) 62 Double (64 bit floating point) 31 Long long (64 bit integer) 31

2011-07-19 OPTISONIC_V6_Modbus_6.doc 14/29

7 DEFAULT SETTINGS

By means of a number of parameters the Modbus communication link can be adjusted to one’s needs or preferences. When the OPTISONIC V6 meter is delivered these parameters are set to default values as listed below:

Port 0:

Baud rate: 19200 Data bits: 8 Stop bits: 1 Parity: Even Modbus Mode: RTU Modbus End Code: 2 Addressing Mode: Modicon compatible Representation Mode: Normal Modbus Address: 237 Modbus Start Gap: 40 (bits) Modbus End Gap: 20 (bits) Modbus Start Code: “:” (colon character) Modbus End Code1: ASCII 13 (carriage return, CR) Modbus End Code2: ASCII 10 (line feed, LF) Modbus Time Out: 1 second

Port 1:

Baud rate: 115200 Data bits: 8 Stop bits: 1 Parity: Even Modbus Mode: RTU Modbus End Code: 2 Addressing Mode: Modicon compatible Representation Mode: Normal Modbus Address: 237 Modbus Start Gap: 40 (bits) Modbus End Gap: 20 (bits) Modbus Start Code: “:” (colon character) Modbus End Code1: ASCII 13 (carriage return, CR) Modbus End Code2: ASCII 10 (line feed, LF) Modbus Time Out: 1 second

KROHNE CT Products

2011-07-19 OPTISONIC_V6_Modbus_6.doc 15/29

8 MODBUS REGISTER MAPPING

Registers are mapped to specific address ranges according to both data and register type:

Data type Register type Read command(s) Write command(s) Address range

Integer (16 bit)

Long integer (32 bit)

Double (64 bit)

Float (32 bit)

Long long (64 bit)

Note: The relative addresses listed in the tables below are addresses relative to the starting address of the designated register group.

8.1 Input Registers (read-only): Integer (16-bit); address range 3000-3499

Input Register 4 n.a. 3000..3499

Holding Register 3 6, 16 3500..3999

Input Register 4 n.a. 5000..5499

Holding Register 3 6, 16 5500..5999

Input Register 4 n.a. 6000..6499

Holding Register 3 6, 16 6500..6999

Input Register 4 n.a. 7000..7499

Holding Register 3 6, 16 7500..7999

Input Register 4 n.a. 8000..8499

Holding Register 3 6, 16 8500..8999

KROHNE CT Products

Parameter / Variable (short description)

Name Explanation

Test register TestRegister uint16

Register reserved for testing communications and protocol handling with this type of register, without affecting the operation of the flow meter.

Relative address

0 3000

Absolute

address,

non-

Modicon

Absolute

address,

Modicon-

comp.

3000-3001

(2 regs)

Units

2011-07-19 OPTISONIC_V6_Modbus_6.doc 16/29

8.2 Holding Registers (read/write): Integer (16-bit); address range 3500-3999 Absolute

Parameter / Variable (short description)

Test register TestRegister uint16

8.3 Input Registers (read-only): Long integer (32-bit); address range 5000-5499

Parameter / Variable (short description)

Test register TestRegister uint32

Alarm / status events

Parameter / Variable (short description)

Down All Channels, no custody transfer standard (FAILED) Down Channels, Custody Transfer unreliable (FAILED) Down Channels, but Custody Transfer reliable

2011-07-19 OPTISONIC_V6_Modbus_6.doc 17/29

Name Explanation

Register reserved for testing communications and protocol handling with this type of register, without affecting the operation of the flow meter.

Name Explanation

Register reserved for testing communications and protocol handling with this type of register, without affecting the operation of the flow meter.

Alarm&Status Pipe 0 A FailAll

Alarm&Status Pipe 1 A FailUnreliable

Alarm&Status Pipe 2 A FailReliable

Bit Name Explanation

Alarm flag indicating none of the acoustic paths is operational.

Alarm flag indicating some paths out of

operation, reading NOT valid for custody transfer measurement.

Alarm flag indicating some paths out of

operation, reading valid for custody

transfer measurement.

Relative address

0 3500

Relative address

0 5000

Relative address

1 5001

address,

non-

Modicon

Absolute

address,

non-

Modicon

Absolute

address,

non-

Modicon

Absolute

address,

Modicon-

comp.

3500-3501

(2 regs)

Absolute

address,

Modicon-

comp.

5000-5001

(2 regs)

Absolute

address,

Modicon-

comp.

5002-5003

(2 regs)

5002-5003

(2 regs)

5002-5003

(2 regs)

Units

[status]

KROHNE CT Products

Parameter / Variable (short description)

Out of range FLOW Alarm&Status Pipe 4 A OOR_Flow

Correction out of range REYNOLDS

Correction out of range PATH SUBSITITION

Flow direction Alarm&Status Pipe 16 S Flow_Direction

Low flow cut-off Alarm&Status Pipe 17 S LowFlowCutOff

Reset occurred: All Totalisers

Channel 1 Unreliable

Channel 1 Down

Channel 1 Down: Deviation SoS too large Channel 1 Down: Signal lost

Alarm&Status Pipe 5 A OOR_Reynolds

Alarm&Status Pipe 6 A OOR_Substit

Alarm&Status Pipe 18 S ResetTotals

Alarm&Status Channel_1 Alarm&Status Channel_1 Alarm&Status Channel_1 Alarm&Status Channel_1

0 A Ch_Unreliable

1 A Ch_Down

2 A Ch_Deviation_SOS

3 A Ch_Signal_Lost

Status signal flow rate is out of range, activated at overspeeding by 25%. Alarm flag indicating Reynolds number out of range Alarm flag indicating gas velocity is out of range where path substitution can be applied. This signal only appears in case of active path substitution (at least one path failing) and gas velocity is out min/max limits OR Reynolds number is out of min/max limits OR no valid velocity profile is available. Status signal indicating flow direction: 0 = Forward flow 1 = Reverse flow Status signal indicating low flow cut-off: 0 = Flow velocity above threshold. 1 = Flow velocity below threshold. Status signal indicating totalisers have been reset. Note: This operation is only allowed for specially authorized personnel. Alarm flag indicating path error (channel

1): channel unreliable. Alarm flag indicating path error (channel

1): channel down. Alarm flag indicating path error (channel

1): SOS deviation too large. Alarm flag indicating path failure (channel 1): signal lost.

Relative address

1 5001

2 5002

Absolute

address,

non-

Modicon

Absolute

address,

Modicon-

comp.

5002-5003

(2 regs)

5002-5003

(2 regs)

5002-5003

(2 regs)

5002-5003

(2 regs)

5002-5003

(2 regs)

5002-5003

(2 regs)

5004-5005

(2 regs)

5004-5005

(2 regs)

5004-5005

(2 regs)

5004-5005

(2 regs)

Units

[status]

KROHNE CT Products

[status]

2011-07-19 OPTISONIC_V6_Modbus_6.doc 18/29

alarm parameter nr 6 set to enabled and

Parameter / Variable (short description)

Channel 2 Unreliable

Channel 2 Down

Channel 2 Down: SoS Deviation too large Channel 2 Down: Signal lost

Channel 3 Unreliable

Channel 3 Down

Channel 3 Down: SoS Deviation too large Channel 3 Down: Signal lost

Reserved Reserved - Reserved Reserved 5-7

Process Temperature Out of range

Process temperature: Override value used

Alarm&Status Channel_2 Alarm&Status Channel_2 Alarm&Status Channel_2 Alarm&Status Channel_2 Alarm&Status Channel_3 Alarm&Status Channel_3 Alarm&Status Channel_3 Alarm&Status Channel_3

Alarm Inputs 0 A_Temperature_OOR

Alarm Inputs 1 A_Temperature_OVR

0 A Ch_Unreliable

1 A Ch_Down

2 A Ch_Deviation_SOS

3 A Ch_Signal_Lost

0 A Ch_Unreliable

1 A Ch_Down

2 A Ch_Deviation_SOS

3 A Ch_Signal_Lost

Alarm flag indicating path error (channel

2): channel unreliable. Alarm flag indicating path error (channel

2): channel down Alarm flag indicating path error (channel

2): SOS deviation too large. Alarm flag indicating path failure (channel 2): signal lost Alarm flag indicating path error (channel

3): channel unreliable. Alarm flag indicating path error (channel

3): channel down. Alarm flag indicating path error (channel

3): SOS deviation too large. Alarm flag indicating path failure (channel 3): signal lost.

Alarm flag, measured body temperature is out of range. Status/alarm flag indicating manual input of temperature value overrides measured temperature (process temperature input); will appear in case

Override Mode (User Control) set to enabled (mode 1 or 2); Mode 3 will not generate an alarm.

Relative address

3 5003

4 5004

8 5008

Absolute

address,

non-

Modicon

5005-5007

(3 regs)

Absolute

address,

Modicon-

comp.

5006-5007

(2 regs)

5006-5007

(2 regs)

5006-5007

(2 regs)

5006-5007

(2 regs)

5008-5009

(2 regs)

5008-5009

(2 regs)

5008-5009

(2 regs)

5008-5009

(2 regs)

5010-5015

(6 regs)

5016-5017

(2 regs)

5016-5017

(2 regs)

Units

[status]

KROHNE CT Products

2011-07-19 OPTISONIC_V6_Modbus_6.doc 19/29

maximum value that can be represented

Parameter / Variable (short description)

Rollover Totaliser Process Forward

Rollover Totaliser Process Reverse

Rollover Totaliser FAIL Process Forward

Rollover Totaliser FAIL Process Reverse

8.4 Holding Registers (read/write): Long integer (32-bit), address range 5500-5999

Parameter / Variable (short description)

Test register TestRegister uint32

Status signal, totaliser has reached

Status Totalisers 1 S_Fwd_Process_Roll

Status Totalisers 5 S_Rev_Process_Roll

Status Totalisers 9 S_FwdFail_Process_Roll

Status Totalisers 13 S_RevFail_Process_Roll

Name Explanation

Register reserved for testing communications and protocol handling with this type of register, without affecting the operation of the flow meter.

and displayed, totalising is continued starting from zero. Status signal, totaliser has reached

and displayed, totalising is continued starting from zero.

Relative address

9 5009

Relative address

0 5500

Absolute

address,

non-

Modicon

Absolute

address,

non-

Modicon

Absolute

address,

Modicon-

comp.

5018-5019

(2 regs)

5018-5019

(2 regs)

5018-5019

(2 regs)

5018-5019

(2 regs)

Absolute

address,

Modicon-

comp.

5500-5501

(2 regs)

Units

[status]

Units

KROHNE CT Products

2011-07-19 OPTISONIC_V6_Modbus_6.doc 20/29

Parameter / Variable (short description)

Date and time ANSI time

8.5 Input Registers (read-only): Double (64-bit floating-point), address range 6000-6499

Parameter / Variable (short description)

Test register

8.6 Holding Registers (read/write): Double (64-bit floating-point), address range 6500-6999

Parameter / Variable (short description)

Test register

Name Explanation

Built-in real time clock: date and time according to ANSI standard: number of seconds elapsed since January 1st, 1970, 00:00:00 hours. Note: Although this is a Holding Register, this register is read-

only. Use the KROHNE Flowmeter Configuration and Monitoring software to set or adjust the real-time clock.

Name Explanation

TestRegister double64

Name Explanation

TestRegister double64

Register reserved for testing communications and protocol handling with this type of register, without affecting the operation of the flow meter.

Relative address

1 5501

Relative address

0 6000

Relative address

0 6500

Absolute

address,

non-

Modicon

Absolute

address,

non-

Modicon

Absolute

address,

non-

Modicon

Absolute

address,

Modicon-

comp.

5502-5503

(2 regs)

Absolute

address,

Modicon-

comp.

6000-6003

(4 regs)

Absolute

address,

Modicon-

comp.

6500-6503

(4 regs)

Units

KROHNE CT Products

Units

2011-07-19 OPTISONIC_V6_Modbus_6.doc 21/29

8.7 Input Registers (read-only): Float (32-bit floating-point), address range 7000-7499

Parameter / Variable (short description)

Test register TestRegister float32

Transit Time Measuring Process Values

Parameter / Variable (short description)

Gain "downstream" (= gain for transducer B), Channel 1-3

Reserved Reserved Reserved 4-6

Gain "upstream" (= gain for transducer A), Channel 1-3

Reserved Reserved Reserved 10-12

SNR "downstream" (=received at trd. B), Channel 1-3

Reserved Reserved Reserved 16-18

SNR "upstream" (=received at trd. A), Channel 1-3

Reserved Reserved Reserved 22-24

Name Explanation

Register reserved for testing communications and protocol handling with this type of register, without affecting the operation of the flow meter.

Name Explanation

Ch_GainAB

Ch_GainBA

Ch_SNratioAB

Ch_SNratioBA

Gain for transmission of signal from transducer A towards transducer B, array with values for channel 1 through 3.

Gain for transmission of signal from transducer B towards transducer A, array with values for channel 1 through 3.

Signal-to-noise ratio for transmission of signal from transducer A towards transducer B, array with values for channel 1 through 3.

Signal-to-noise ratio for transmission of signal from transducer B towards transducer A, array with values for channel 1 through 3.

Relative address

0 7000

Relative address

1-3

7-9

13-15

19-21

Absolute

address,

non-

Modicon

Absolute

address,

non-

Modicon

7001-7003

(3 regs)

7004-7006

(3 regs)

7007-7009

(3 regs)

7010-7012

(3 regs)

7013-7015

(3 regs)

7016-7018

(3 regs)

7019-7021

(3 regs)

7022-7024

(3 regs)

Absolute

address,

Modicon-

comp.

7000-7001

(2 regs)

Absolute

address,

Modicon-

comp.

7002-7007

(6 regs)

7008-7013

(6 regs)

7014-7019

(6 regs)

7020-7025

(6 regs)

7026-7031

(6 regs)

7032-7037

(6 regs)

7038-7043

(6 regs)

7044-7049

(6 regs)

Units

KROHNE CT Products

2011-07-19 OPTISONIC_V6_Modbus_6.doc 22/29

Measured / entered process parameters

Absolute

Parameter / Variable (short description)

Temperature process value TemperatureProces

Dynamic Viscosity at Process conditions

Density Process DensityProces

Calculated flow variables

Parameter / Variable (short description)

Flow Process Flow_Proces Measured volume flow rate at process conditions. 28 7028

Velocity Process Velo_Proces

Speed of Sound SoS

Channel Velocity, Channel 1-3 Ch_VeloRaw

Reserved Reserved Reserved 34-36

Channel SOS, Channel 1-3 Ch_SoS

Name Explanation

Value used for calculations, can either be the measured process value, a calculated (indirectly determined) value or a manual setting (fixed value).

ViscosityDynamicProces

Name Explanation

Value used for calculations, can either be the measured process value, a calculated (indirectly determined) value or a manual setting (fixed value). Value used for calculations, can either be the measured process value, a calculated (indirectly determined) value or a manual setting (fixed value).

Measured gas velocity (integrated value from all paths) at process conditions. Measured speed of sound, average of all acoustic paths, corrected for mach effect. “Raw” gas velocity as observed on each channel; array with values for channel 1 through 3.

Speed of sound as observed on each channel; array with values for channel 1 through 3.

Relative address

25 7025

26 7026

27 7027

Relative address

29 7029

30 7030

31-33

37-39

7031-7033

7034-7036

7037-7039

address,

non-

Modicon

Absolute

address,

non-

Modicon

(3 regs)

Absolute

address,

Modicon-

comp.

7050-7051

(2 regs)

7052-7053

(2 regs)

7054-7055

(2 regs)

Absolute

address,

Modicon-

comp.

7056-7057

(2 regs)

7058-7059

(2 regs)

7060-7061

(2 regs)

7062-7067

(6 regs)

7068-7073

(6 regs)

7074-7079

(6 regs)

Units

°C

kg/m3

Units

m3/s

m/s

KROHNE CT Products

2011-07-19 OPTISONIC_V6_Modbus_6.doc 23/29

Absolute

Parameter / Variable (short description)

Reserved Reserved Reserved 40-42

Statistics / diagnostics variables

Averages and standard deviations are calculated for a number of flow variables. The number of measurement values that are included in this calculation are specified by means of a preset parameter. Averages and standard deviations are evaluated and updated each time a number of measurements equal to this parameter has been collected. Collecting data for a new block of data to be evaluated then starts again from there.

As an exception to the rule above, for the flow standard deviation tau, the preset number of measurement values is evaluated every time a new measurement value becomes available. The series of measurements values then contains the most recent values and shifts with each acquired sample (measurement data), like a running average.

Parameter / Variable (short description)

Channel reliability, channel 13

Reserved Reserved Reserved 46-48

Channel velocity, average, channel 1-3

Reserved Reserved Reserved 52-54

Channel SoS, average, channel 1-3

Reserved Reserved Reserved 58-60

SoS Average AV_SoS Speed of Sound value, average. 61 7061

Name Explanation

Ch_Reliab Reliability per channel; array with values for channel 1 through 3 43-44

Ch_AV_Velocity

Ch_AV_SoS

Average gas velocity, as observed on each channel; array with values for channel 1 through 3.

Average speed-of-sound, as observed on each channel; array with values for channel 1 through 3.

Relative address

49-51

55-57

address,

non-

Modicon

7040-7042

(3 regs)

Absolute

address,

non-

Modicon

7043-7045

(3 regs)

7046-7048

(3 regs)

7049-7051

(3 regs)

7052-7054

(3 regs)

7055-7057

(3 regs)

7058-7060

(3 regs)

Absolute

address,

Modicon-

comp.

7080-7085

(6 regs)

Absolute

address,

Modicon-

comp.

7086-7091

(6 regs)

7092-7097

(6 regs)

7098-7103

(6 regs)

7104-7109

(6 regs)

7110-7115

(6 regs)

7116-7121

(6 regs)

7122-7123

(2 regs)

Units

m/s

KROHNE CT Products

2011-07-19 OPTISONIC_V6_Modbus_6.doc 24/29

The reliabilities of the individual paths are combined in an overall

Absolute

Parameter / Variable (short description)

Flow average AV_FlowProces Volume flow rate value, average. 62 7062

Flow standard deviation SD_FlowProces Standard deviation of volume flow rate (“batchwise calculation”).

Flow standard deviation Tau SD_FlowProcesTau Standard deviation of volume flow rate ("running calculation”). 64 7064

SoS standard deviation SD_SoS Speed of Sound standard deviation. 65 7065

Channel velocity, standard deviation, channel 1-3

Reserved Reserved Reserved 69-71

Channel SoS, standard deviation, channel 1-3

Reserved Reserved Reserved 75-77

Overall weighted reliability Weighted_Reliability

8.8 Holding Registers (read/write): Float (32-bit) floating-point, address range 7500-7999

Parameter / Variable (short description)

Test register TestRegister float32

Name Explanation

Ch_SD_Velocity

Ch_SD_SoS

Name Explanation

Gas velocity, standard deviation, as observed on each channel; array with values for channel 1 through 3.

Speed of Sound, standard deviation, as observed on each channel; array with values for channel 1 through 3.

figure using the weighing factors of the paths.

Register reserved for testing communications and protocol handling with this type of register, without affecting the operation of the flow meter.

Relative address

63 7063

66-68

72-74

78 7078

Relative address

7066-7068

7069-7071

7072-7074

7075-7077

0 7500

address,

non-

Modicon

(3 regs)

Absolute

address,

non-

Modicon

Absolute

address,

Modicon-

comp.

7124-7125

(2 regs)

7126-7127

(2 regs)

7128-7129

(2 regs)

7130-7131

(2 regs)

7132-7137

(6 regs)

7138-7143

(6 regs)

7144-7149

(6 regs)

7150-7155

(6 regs)

7156-7157

(2 regs)

Absolute

address,

Modicon-

comp.

7500-7501

(2 regs)

Units

m3/s

Units

KROHNE CT Products

2011-07-19 OPTISONIC_V6_Modbus_6.doc 25/29

Flowmeter configuration

Absolute

Parameter / Variable (short description)

Internal diameter Diameter Internal diameter of meter body at the measuring section. 1 7501

Meter Constant forward MeterConstant_Fwd Meter constant, forward flow direction. 2 7502

Meter Constant reverse MeterConstant_Rev Meter constant, reverse flow direction. 3 7503

Thermal expansion factor pipe material Alpha Reference temperature Body expansion Channel Calibrated Path Length L, channel 1-3

Reserved Reserved Reserved 9-11

Channel Measuring Angle, channel 1-3

Reserved Reserved Reserved 15-17

Flow Full Scale Forward Fwd_MaxFlowRate

Flow Full Scale Reverse Rev_MaxFlowRate

Low Flow cutoff Forward Fwd_LowFlowCutoff

Low Flow cutoff Reverse Rev_LowFlowCutoff

2011-07-19 OPTISONIC_V6_Modbus_6.doc 26/29

Name Explanation

ThermExp_Alpha_Pipe

ThermExp_ReferenceTemp

Ch_PathLength_Cal

Ch_Angle_Measuring

Property of the material of the meter body, used to calculate the effect of thermal expansion. Temperature at which the internal diameter of meter body at the measuring section is specified. Length of acoustic path length between two transducers of a measuring path; array with values for channel 1 through 3.

Angle at which the ultrasonic beam intersects with the meter body; array with values for channel 1 through 3.

Indicated value (full scale) at flow of 100% of rated volume flow in forward flow direction Indicated value (full scale) at flow of 100% of rated volume flow in reverse flow direction For forward flow rates with smaller magnitude than this cutoff value, totalisers stop counting and outputs (such as the frequency output) will be disabled; flow rate indication will still be available For reverse flow rates with smaller magnitude than this cutoff value, totalisers stop counting and outputs (such as the frequency output) will be disabled; flow rate indication will still be available

Relative address

4 7504

5 7505

6-8

12-14

18 7518

19 7519

20 7520

21 7521

7506-7508

7509-7511

7512-7514

7515-7517

address,

non-

Modicon

(3 regs)

Absolute

address,

Modicon-

comp.

7502-7503

(2 regs)

7504-7505

(2 regs)

7506-7507

(2 regs)

7508-7509

(2 regs)

7510-7511

(2 regs)

7512-7517

(6 regs)

7518-7523

(6 regs)

7524-7529

(6 regs)

7530-7535

(6 regs)

7536-7537

(2 regs)

7538-7539

(2 regs)

7540-7541

(2 regs)

7542-7543

(2 regs)

Units

1/°C

°C

Deg

m3/s

m/s

KROHNE CT Products

Parameter / Variable (short description)

Low Flow cutoff Threshold

Alarm configuration

Parameter / Variable (short description)

Allowed Deviation SOS per channel on SOS average Pipe

Input Temperature Proces: LimitHigh Input Temperature Proces: LimitLow

Viscosity configuration

Parameter / Variable (short description)

Dynamic Viscosity at Reference Temperature

Reference Density D_Reference_Dens

Name Explanation

Low_Flowcut_ThresHold

Name Explanation

SOSDev

T_LimitHigh Upper limit for process temperature measurement. 24 7524

T_LimitLow Lower limit for process temperature measurement. 25 7525

Name Explanation

VD_Reference_Visc

Hysteresis preventing frequent on/off switching of low flow cut-off

Defines alarm limit for deviation of measured SOS of any acoustic path from average value of all paths (all SoS values calculated with mach-correction).

Input value of dynamic viscosity, used as base value to correct reference viscosity to actual viscosity at process temperature and pressure. Input value of density, used as base value to correct reference density to actual density at process temperature and pressure.

Relative address

22 7522

Relative address

23 7523

Relative address

26 7526

27 7527

Absolute

address,

non-

Modicon

Absolute

address,

non-

Modicon

Absolute

address,

non-

Modicon

Absolute

address,

Modicon-

comp.

7544-7545

(2 regs)

Absolute

address,

Modicon-

comp.

7546-7547

(2 regs)

7548-7549

(2 regs)

7550-7551

(2 regs)

Absolute

address,

Modicon-

comp.

7552-7553

(2 regs)

7554-7555

(2 regs)

Units

KROHNE CT Products

m/s

°C

Units

kg/m3

2011-07-19 OPTISONIC_V6_Modbus_6.doc 27/29

erature value, to be taken into effect in case of

Override control

Parameter / Variable (short description)

Temperature Process Manual override value

8.9 Input Registers (read-only): Long long (64-bit integer), address range 8000-8499

Name Explanation

Ovr_Value_T

Manually set temp failing temperature measurement

Relative address

28 7528

Absolute

address,

non-

Modicon

Absolute

address,

Modicon-

comp.

7556-7557

(2 regs)

Units

°C

Absolute

Parameter / Variable (short description)

Test register TestRegister uint64

Totalisers

Parameter / Variable (short description)

Totaliser PROCESS Forward Fwd_Proces

Totaliser PROCESS Reverse Rev_Proces

Totaliser FAIL PROCESS Forward Totaliser FAIL PROCESS Reverse

2011-07-19 OPTISONIC_V6_Modbus_6.doc 28/29

Name Explanation

Register reserved for testing communications and protocol handling with this type of register, without affecting the operation of the flow meter.

Name Explanation

Accumulated volume (with normal working meter) in forward flow direction, at line conditions. Accumulated volume (with normal working meter) in reverse flow direction, at line conditions.

FwdFail_Proces

RevFail_Proces

Accumulated volume (with meter in error state) in forward flow direction, at line condition. Accumulated volume (with meter in error state) in reverse flow direction, at line condition.

Relative address

0 8000

Relative address

1 8001

2 8002

3 8003

4 8004

address,

non-

Modicon

Absolute

address,

non-

Modicon

Absolute

address,

Modicon-

comp.

8000-8003

(4 regs)

Absolute

address,

Modicon-

comp.

8004-8007

(4 regs)

8008-8011

(4 regs)

8012-8015

(4 regs)

8016-8019

(4 regs)

Units

(=10-6 m3)

KROHNE CT Products

8.10 Holding Registers (read/write): Long long (64-bit integer), address range 8500-8999

Parameter / Variable (short description)

Test register TestRegister uint64

Name Explanation

Register reserved for testing communications and protocol handling with this type of register, without affecting the operation of the flow meter.

Relative address

0 8500

Absolute

address,

non-

Modicon

Absolute

address,

Modicon-

comp.

8500-8503

(4 regs)

Units

KROHNE CT Products

2011-07-19 OPTISONIC_V6_Modbus_6.doc 29/29

KROHNE OPTISONIC-V6 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual