FieldServer FS-8700-08 User Manual

APPLICABILITY & EFFECTIVITY

Effective for all systems manufactured after January 2013

Driver Manual

(Supplement to the FieldServer Instruction Manual)

FS-8700-01 Modbus RTU

&

FS-8700-08 Modbus ASCII

There are several similarities between these two drivers and we have

incorporated them into the same manual to ensure that our information

stays current. Although both drivers are referenced in this manual, they are

different drivers and need to be ordered separately."

Driver Version:

4.06

Document Revision:

3

A Sierra Monitor Company

FS-8700-01 Modbus RTU/ASCIIFS-8700-01_Modbus_RTU.doc Driver Manual Table of Contents

TABLE OF CONTENTS

1 Modbus RTU/ Modbus ASCII Description ....................................................................................................... 3

2 Driver Scope of Supply ................................................................................................................................... 3

2.1 Supplied by FieldServer Technologies for this driver ................................................................................... 3

2.2 Provided by Supplier of 3rd Party Equipment ............................................................................................... 3

3 Hardware Connections ................................................................................................................................... 4

4 Data Array Parameters ................................................................................................................................... 5

5 Configuring the FieldServer as a Modbus RTU or Modbus ASCII Client. .......................................................... 6

5.1 Client Side Connection Parameters .............................................................................................................. 6

5.2 Client Side Node Parameters ....................................................................................................................... 7

5.3 Client Side Map Descriptor Parameters ....................................................................................................... 8

5.3.1 FieldServer Related Map Descriptor Parameters ..................................................................................... 8

5.3.2 Driver Related Map Descriptor Parameters ............................................................................................. 8

5.3.3 Timing Parameters ................................................................................................................................... 9

5.3.4 Map Descriptor Examples. ..................................................................................................................... 10

6 Configuring the FieldServer as a Modbus RTU or Modbus ASCII Server ........................................................ 11

6.1 Server Side Connection Parameters ........................................................................................................... 11

6.2 Server Side Node Parameters .................................................................................................................... 12

6.3 Server Side Map Descriptor Parameters .................................................................................................... 13

6.3.1 FieldServer Specific Map Descriptor Parameters ................................................................................... 13

6.3.2 Driver Specific Map Descriptor Parameters ........................................................................................... 13

6.3.3 Map Descriptor Examples ...................................................................................................................... 14

6.3.4 Slave_Id .................................................................................................................................................. 14

Appendix A. Useful Features – Modbus RTU ........................................................................................................ 15

Appendix A.1. Managing Floating points with Modbus ........................................................................................... 15

Appendix A.1.1. Transferring non-integer values with one register ................................................................. 15

Appendix A.1.2. Transferring 32 bit values with two registers ......................................................................... 16

Appendix A.2. Node_Offline_Response................................................................................................................... 16

Appendix B. Troubleshooting ............................................................................................................................... 18

Appendix B.1. Server Configuration of System Station Address.............................................................................. 18

Appendix C. Vendor Information ......................................................................................................................... 19

Appendix C.1. Connection to York Modbus Microgateway ..................................................................................... 19

Appendix C.2. Modbus ASCII - Examples of FieldServer setup for typical clients .................................................... 19

Appendix C.2.1. FieldServer with GE Cimplicity as client .................................................................................. 19

Appendix C.2.2. FieldServer with Intellution FIX as a client .............................................................................. 19

Appendix D. Reference ........................................................................................................................................ 21

Appendix D.1. Data Types ........................................................................................................................................ 21

Appendix D.2. Single Writes .................................................................................................................................... 21

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FieldServer Technologies PART #

Description

FS-8915-10

UTP cable (7 foot) for RS-232 use 1

PART #

Description

Modbus RTU or Modbus ASCII device

1

1 MODBUS RTU/ M O D B US ASCII DE SC R I P TION

The Modbus RTU and Modbus ASCII drivers allow the FieldServer to transfer data to and from devices using
Modbus RTU or Modbus ASCII protocol respectively. Data can be transferred over either RS-232 or RS-485. The
driver was developed for Modbus Application Protocol Specification V1.1a" from Modbus-IDA. The specification
can be found at www.modbus.org. The FieldServer can emulate either a Server or Client.

The information that follows describes how to expand upon the factory defaults provided in the configuration files
included with the FieldServer.

There are various register mapping models being followed by various vendors

To cover all these models FieldServer uses the following three Models

 Modicon_5digit – Use this format where addresses are defined in 0xxxx, 1xxxx, 3xxxx or 4xxxx format. A

maximum of 9999 registers can be mapped of each type. This is FieldServer driver’s default format.

 ADU –Application Data Unit address. Use this format where addresses of each type are defined in the

range 1-65536

 PDU –Protocol Data unit address. Use this format where addresses of each type are defined in the range

0-65535.

The key difference between ADU and PDU is for example if Address_Type is ADU and address is 1, the driver will
poll for register 0. If Address_Type is PDU, the driver will poll for address 1.

Note 1: If vendor document shows addresses in extended Modicon (i.e. 6 digit) format like 4xxxxx then consider
these addresses as xxxxx (omit the first digit) and use either ADU or PDU

Note 2: The purpose of providing 3 different ways of addressing the Modbus registers is to allow the user to
choose the addressing system most compatible with the address list being used. At the protocol level, the same
protocol specification is used for all three with the exception of the limited address range for Modicon_5digit.

2 DRIVER SCOPE OF SU P PLY

2.1 Sup plied by FieldSe r v e r Technologies fo r t h i s driver

2.2 Provided by Supplier of 3

rd

Party Equipment

This cable is necessary for connection to the driver. It is shipped with the FieldServer and not separately with the driver.

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FS-8700-01 Modbus RTU/ASCIIFS-8700-01_Modbus_RTU.doc Driver Manual Page 4 of 21

RJ45 to

RS-232

Connector

Connect

to 2-wire

RS-485

network

OR

RJ45 Connector

Typical DB9/DB25
kit assemblies are
shown here. Refer
to the third party
device literature
for exact
configuration

required.

DB25M

FUNCTION FROM TO COLOUR

Rx RJ45-01 DB9F-03 WHITE

GND RJ45-04 DB9F-05 GREEN

Tx RJ45-08 DB9F-02 BLUE

FUNCTION FROM TO COLOUR

RX RJ45-01 DB25M-03 WHITE
CTS RJ45-02 DB25M-05 BROWN
DSR RJ45-03 YELLOW
GND RJ45-04 DB25M-07 GREEN
GND RJ45-05 RED

TX RJ45-08 DB25M-02 BLUE

RTS RJ45-07 DB25M-04 ORANGE

DTR RJ45-06 BLACK

8917-01 WIRE LIST

FUNCTION FROM TO COLOUR

RX RJ45-01 DB25F-02 WHITE
CTS RJ45-02 DB25F-04 BROWN
DSR RJ45-03 YELLOW
GND RJ45-04 DB25F-07 GREEN
GND RJ45-05 RED

TX RJ45-08 DB25F-03 BLUE

RTS RJ45-07 DB25F-05 ORANGE

DTR RJ45-06 BLACK

8917-04 WIRE LIST

DB25F

DB9M

FUNCTION FROM TO COLOUR

RX RJ45-01 DB9M-02 GREY
CTS RJ45-02 DB9M08 BROWN
DSR RJ45-03 DB9M-06 YELLOW
GND RJ45-04 DB9M-05 GREEN
GND RJ45-05 RED

TX RJ45-08 DB9M-03 BLUE

RTS RJ45-07 DB9M-07 ORANGE

DTR RJ45-06 DB9M-04 BLACK

8917-03 WIRE LIST

BASE NAME:
FILE NAME:

FIELDSERVER

GENERIC

CONNECTION DIAGRAM

DATE: 8/16/05
BY: MC

(408)-262-2299

DB9F

8917-02 WIRE LIST

PLC

Ethernet Interface

FS-8915-10

FS-8915-10

Site Ethernet

2

3 HARDWARE C O N N E CT ION S

It is possible to connect a Modbus RTU or Modbus ASCII device to any of the existing serial ports on the
FieldServer2. These ports simply need to be configured for the appropriate driver in the configuration file.

Configure the Modbus RTU or Modbus ASCII device according to manufacturer’s instructions.

Not all ports shown are necessarily supported by the hardware. Consult the appropriate Instruction manual for details of the ports available

on specific hardware.

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Section Title

Data_Arrays

Column Title

Function

Legal Values

Data_Array_Name

Provide name for Data Array

Up to 15 alphanumeric characters

Data_Array_Format

Provide data format. Each Data Array can only take
on one format.

FLOAT, BIT, UInt16, SInt16,
Packed_Bit, Byte, Packed_Byte,
Swapped_Byte

Data_Array_Length

Number of Data Objects. Must be larger than the
data storage area required by the Map Descriptors
for the data being placed in this array.

1-10, 000
// Data Arrays

Data_Arrays

Data_Array_Name

, Data_Array_Format

, Data_Array_Length

DA_AI_01

, UInt16

, 200

DA_AO_01

, UInt16

, 200

DA_DI_01

, Bit

, 200

DA_DO_01

, Bit

, 200

4 DATA A R R AY PARAMETERS

Data Arrays are “protocol neutral” data buffers for storage of data to be passed between protocols. It is necessary

to declare the data format of each of the Data Arrays to facilitate correct storage of the relevant data.

Example

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Section Title

Connections

Column Title

Function

Legal Values

Port

Specify which port the device is connected to the FieldServer

P1-P8, R1-R23

Baud*

Specify baud rate

110 – 115200, standard baud
rates only. 9600

Parity*

Specify parity

Even, Odd, None

Data_Bits*

Specify data bits

7, 8

Stop_Bits*

Specify stop bits

1,2

Protocol

Specify protocol used

Modbus RTU

Modbus _RTU

Modbus ASCII

MB_ASCII

Poll_Delay*

Time between internal polls

0-32000s, 0.05s

// Client Side Connections

Connections

Port

, Baud

, Parity

, Data_Bits

, Stop_Bits

, Protocol

, Handshaking

, Poll_Delay

P1

, 9600

, None

, 8

, 1

, Modbus _RTU4

, None

, 0.100s

3

4

5 CONFIGUR I N G T HE FIELDSERVER A S A M O DBUS RTU OR MODB U S A SCII CLIENT.

For a detailed discussion on FieldServer configuration, please refer to the FieldServer Configuration Manual. The
information that follows describes how to expand upon the factory defaults provided in the configuration files
included with the FieldServer (See “.csv” sample files provided with the FieldServer).

This section documents and describes the parameters necessary for configuring the FieldServer to communicate
with a Modbus RTU or Modbus ASCII Server.

5.1 Client Side Connect ion Parameters

Example

Not all ports shown are necessarily supported by the hardware. Consult the appropriate Instruction manual for details of the ports available

on specific hardware.

Change protocol to MB_ASCII to use Modbus ASCII protocol

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Section Title

Nodes

Column Title

Function

Legal Values

Node_Name

Provide name for Node

Up to 32 alphanumeric
characters

Node_ID

Modbus station address of physical Server Node

1-255

Protocol

Specify protocol used

Modbus RTU

Modbus_RTU

Modbus ASCII

MB_ASCII

Port

Specify which port the device is connected to the FieldServer

P1-P8, R1-R2

3

Address_Type5

Specify Register Mapping Model

ADU,PDU, -,

Modicon_5digit

Write_Fnc*

Set to Multiple if Remote Server Node only supports Write Multiple
function code 15 & 16

Multiple, -,

Write_Length*

Set to Map Descriptor Length if write-thru operation should write
all registers as specified by Map Descriptor length.
By default write-thru writes a single register.
If Write_Length also specified on Map Descriptor, Map Descriptor’s
parameter will be used.

Map Descriptor Length, -,
1,

// Client Side Nodes

// For devices where 65536 addresses are available in each memory area.

Nodes

Node_Name

, Node_ID

, Protocol

, Port

,Address_Type

Modbus device 1

, 1

, Modbus _RTU6

, P1

,ADU

Modbus device 2

, 2

, Modbus_RTU

, P1

,PDU

// For devices where only 9999 registers are available in each memory area.

Nodes

Node_Name

, Node_ID

, Protocol

, Port

Modbus device 3

, 3

, Modbus_RTU

, P1

5

6

5.2 Client Side Node P a r a m eters

Example:

Optional for Modicon 5 digit devices
Change protocol to MB_ASCII to use Modbus ASCII protocol

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Column Title

Function

Legal Values

Map_Descriptor_Name

Name of this Map Descriptor

Up to 32 alphanumeric characters

Data_Array_Name

Name of Data Array where data is
to be stored in the FieldServer

One of the Data Array names from Section 4

Data_Array_Offset

Starting location in Data Array

0 to (Data_Array_Length -1) as specified in Section
4

Function

Function of Client Map
Descriptor.

Wrbc, Wrbx, Rdbc, Arcs. Refer to Error! Reference
source not found. for more information.

Column Title

Function

Legal Values

Node_Name

Name of Node to fetch data from

One of the Node names specified in
“Client Node Descriptor” above

Data_Type7

Specify memory area. Refer to Appendix
A.1.2 on how to transfer 32 Bit values
using Modbus registers.

Address_Type = ADU

Coil, Discrete_Input, Input_Register,
Holding_Register, Single_Coil,
Single_Register, Slave_Id

Address_Type = PDU

FC01, FC02, FC03, FC04,
FC05, FC06, FC15, FC16

Address_Type = Modicon_5digit

- (Dash), Single_Register, Single_Coil

All Address_Type

Float_Reg, 32-Bit_Reg, Input_Float,
Input_Reg_32Bit

Address

Starting address of read block

Address_Type = ADU

1-65536

Address_Type = PDU

0-65535

Address_Type = Modicon_5digit

40001, 30001, etc

Length

Length of Map Descriptor.

1-125 (For Analog polls),
1-800 (For Binary polls).

Write_Length*

Set to Map Descriptor Length if write-thru
operation should write all registers as
specified by length parameter.
By default write-thru writes a single
register.

Map Descriptor Length, 1,

Data_Array_Low_Scale*

Scaling zero in Data Array

Any signed 32 bit integer in the range:

7

5.3 Client Side Map Desc r i p t o r Parameters

5.3.1 FieldServer Relat e d M a p Descriptor Paramete r s

5.3.2 Driver Related Map De s c r i p t o r Parameters

Optional only for Modicon_5digit addressing, and only if Single writes do not need to be forced

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-2,147,483,648 to 2,147,483,647. 0

Data_Array_High_Scale*

Scaling max in Data Array

Any signed 32 bit integer in the range:

-2,147,483,648 to 2,147,483,647. 100

Node_Low_Scale*

Scaling zero in Connected Node

Any signed 32 bit integer in the range:

-2,147,483,648 to 2,147,483,647. 0

Node_High_Scale*

Scaling max in Connected Node

Any signed 32 bit integer in the range:

-2,147,483,648 to 2,147,483,647. 100

Column Title

Function

Legal Values

Scan_Interval*

Rate at which data is polled

0-32000, 1

5.3.3 Timing Parameters

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// Client Side Map Descriptors

// Note: All three examples below are addressing the same Modbus registers.

// For Nodes where Address_Type is ADU

Map_Descriptors

Map_Descriptor_Name

, Data_Array_Name

, Data_Array_Offset

, Function

, Node_Name

, Data_Type

, Address

, Length

,Scan_Interval

CMD_AI_01

, DA_AI_01

, 0

, Rdbc

, MODBUS DEVICE1

, Input_Register

, 1

, 20

,1.000s

CMD_AO_01

, DA_AO_01

, 0

, Rdbc

, MODBUS DEVICE1

, Holding_Register

, 1

, 20

,1.000s

CMD_DI_01

, DA_DI_01

, 0

, Rdbc

, MODBUS DEVICE1

, Discrete_Input

, 1

, 20

,1.000s

CMD_DO_01

, DA_DO_01

, 0

, Rdbc

, MODBUS DEVICE1

, Coil

, 1

, 20

,1.000s

// For Nodes where Address_Type is PDU

Map_Descriptors

Map_Descriptor_Name

, Data_Array_Name

, Data_Array_Offset

, Function

, Node_Name,

, Data_Type

, Address

, Length

,Scan_Interval

CMD_AI_02

, DA_AI_02

, 0

, Rdbc

, MODBUS DEVICE2

, FC04

, 0

, 20

,1.000s

CMD_AO_02

, DA_AO_02

, 0

, Rdbc

, MODBUS DEVICE2

, FC03

, 0

, 20

,1.000s

CMD_DI_02

, DA_DI_02

, 0

, Rdbc

, MODBUS DEVICE2

, FC02

, 0

, 20

,1.000s

CMD_DO_02

, DA_DO_02

, 0

, Rdbc

, MODBUS DEVICE2

, FC01

, 0

, 20

,1.000s

// For Nodes where Address_Type is Modicon_5digit.

Map_Descriptors

Map_Descriptor_Name

, Data_Array_Name

, Data_Array_Offset

, Function

, Node_Name,

, Address

, Length

, Scan_Interval

CMD_AI_03

, DA_AI_03

, 0

, Rdbc

, MODBUS DEVICE3

, 30001

, 20

, 1.000s

CMD_AO_03

, DA_AO_03

, 0

, Rdbc

, MODBUS DEVICE3

, 40001

, 20

, 1.000s

CMD_DI_03

, DA_DI_03

, 0

, Rdbc

, MODBUS DEVICE3

, 10001

, 20

, 1.000s

CMD_DO_03

, DA_DO_03

, 0

, Rdbc

, MODBUS DEVICE3

, 00001

, 20

, 1.000s

5.3.4 Map Descriptor Exam pl e s.

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Section Title

Connections

Column Title

Function

Legal Values

Port

Specify which port the device is connected
to the FieldServer

P1-P8, R1-R28
Baud*

Specify baud rate

110 – 115200, standard baud rates only, 9600

Parity*

Specify parity

Even, Odd, None

Data_Bits*

Specify data bits

7, 8

Stop_Bits*

Specify stop bits

1, 2

Protocol

Specify protocol used

Modbus RTU

Modbus_RTU

Modbus ASCII

MB_ASCII

// Server Side Connections

Connections

Port

, Baud

, Parity

, Data_Bits

, Stop_Bits

, Protocol

P1

, 9600

, None

, 8

, 1

, Modbus_RTU

8

6 CONFIGUR I N G T HE FIELDSERVER A S A M O DBUS RTU OR MODBUS A SCII SERVER

For a detailed discussion on FieldServer configuration, please refer to the FieldServer Configuration Manual. The
information that follows describes how to expand upon the factory defaults provided in the configuration files
included with the FieldServer (See “.csv” sample files provided with the FieldServer).

This section documents and describes the parameters necessary for configuring the FieldServer to communicate
with a Modbus RTU or Modbus ASCII Client.

The configuration file tells the FieldServer about its interfaces, and the routing of data required. In order to enable
the FieldServer for Modbus RTU or Modbus ASCII communications, the driver independent FieldServer buffers

need to be declared in the “Data Arrays” section, the FieldServer virtual Node(s) needs to be declared in the
“Server Side Nodes” section, and the data to be provided to the clients needs to be mapped in the “ Server Side
Map Descriptors” section. Details on how to do this can be found below.

Note that in the tables, * indicates an optional parameter, with the bold legal value being the default.

6.1 Server Side Connectio n Parameters

Example

Change protocol to MB_ASCII to use Modbus ASCII protocol

Not all ports shown are necessarily supported by the hardware. Consult the appropriate Instruction manual for details of the ports available

on specific hardware.

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Section Title

Nodes

Column Title

Function

Legal Values

Node_Name

Provide name for Node

Up to 32 alphanumeric
characters

Node_ID

Node ID of physical Server Node

1 – 255

Protocol

Specify protocol used

Modbus RTU

Address_Type9

Specify Register Mapping Model

ADU,PDU, -,

Modicon_5digit

Node_Offline_Response*

Set the FieldServer response to the Modbus RTU
Client when the Server Node supplying the data has
gone offline

No_Response,
Old_Data,
Zero_Data,
FFFF_Data,
Refer to Appendix A.2 for
further information.

Node_Description*

Specify Node description text

Any string up to 99
characters long, -

// Server Side Nodes

// For devices where 65536 addresses are available in each memory area.

Nodes

Node_Name

, Node_ID

, Protocol

, Address_Type

MB_Srv_11

, 11

, Modbus_RTU

, ADU

MB_Srv_12

, 12

, Modbus_RTU

, PDU

// For devices where only 9999 registers are available in each memory area.

Nodes

MB_Srv_13

, 13

, Modbus_RTU

, Modicon_5digit

MB_Srv_14

, 14

, Modbus_RTU

, -

9

6.2 Server Side Node P a r a m eters

Example

Change protocol to MB_ASCII to use Modbus ASCII protocol

Optional for Modicon 5 digit devices

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Column Title

Function

Legal Values

Map_Descriptor_Name

Name of this Map Descriptor

Up to 32 alphanumeric characters

Data_Array_Name

Name of Data Array where data is to be
stored in the FieldServer

One of the Data Array names from
Section 4

Data_Array_Offset

Starting location in Data Array

0 to (Data_Array_Length -1) as specified
in Section 4

Function

Function of Server Map Descriptor

Passive

Column Title

Function

Legal Values

Node_Name

The name of the Node
being represented.

One of the Node names specified in Section 6.2

Data_Type10

Specify memory area

Address_Type = ADU

Coil, Discrete_Input, Input_Register, Holding_Register,
Single_Coil, Single_Register, Slave_ID

Address_Type = PDU

FC01, FC02, FC03, FC04,
FC05, FC06, FC15, FC16

Address_Type = Modicon_5digit

- (Dash), Single_Register, Single_Coil

Length*

Length of Map Descriptor

1-10000, 1

Address

Starting address of read
block

Address_Type = ADU

1-65536

Address_Type = PDU

0-65535

Address_Type = Modicon_5digit

40001, 30001, etc

Data_Array_Low_Scale*

Scaling zero in Data Array

Any signed 32 bit integer in the range:

-2,147,483,648 to 2,147,483,647. 0

Data_Array_High_Scale*

Scaling max in Data Array

Any signed 32 bit integer in the range:

-2,147,483,648 to 2,147,483,647. 100

Node_Low_Scale*

Scaling zero in Connected
Node

Any signed 32 bit integer in the range:

-2,147,483,648 to 2,147,483,647. 0

Node_High_Scale*

Scaling max in Connected
Node

Any signed 32 bit integer in the range:

-2,147,483,648 to 2,147,483,647. 100

10

6.3 Server Side Map Descri pt o r Parameters

6.3.1 FieldServer Speci f i c M ap Descriptor Param e t e r s

6.3.2 Driver Specific Map D e s c r i p t o r Parameters

Optional only for Modicon_5digit addressing, and only if Single writes do not need to be forced

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// Server Side Map Descriptors where Node Address_Type is ADU

// Note: All three examples below are addressing the same Modbus registers.

// For Nodes where Address_Type is ADU

Map_Descriptors

Map_Descriptor_Name

, Data_Array_Name

, Data_Array_Offset

, Function

, Node_Name

, Data_Type

, Address

, Length

, Data_Array_Low_Scale

, Data_Array_High_Scale

, Node_Low_Scale

, Node_High_Scale

SMD_AI_01

, DA_AI_01

, 0

, Passive

, MB_Srv_11

, Input_Register

, 1

, 200

, 0

, 100

, 0

, 10000

SMD_AO_01

, DA_AO_01

, 0

, Passive

, MB_srv_11

, Holding_Register

, 1

, 200

, 0

, 100

, 0

, 10000

// Server Side Map Descriptors where Node Address_Type is PDU

Map_Descriptors

Map_Descriptor_Name

, Data_Array_Name

, Data_Array_Offset

, Function

, Node_Name

, Data_Type

, Address

, Length

, Data_Array_Low_Scale

, Data_Array_High_Scale

, Node_Low_Scale

, Node_High_Scale

SMD_AI_02

, DA_AI_02

, 0

, Passive

, MB_Srv_12

, FC04

, 0

, 200

, 0

, 100

, 0

, 10000

SMD_AO_02

, DA_AO_02

, 0

, Passive

, MB_srv_12

, FC03

, 0

, 200

, 0

, 100

, 0

, 10000

// For Nodes where Address_Type is Modicon_5digit.

Map_Descriptors

Map_Descriptor_Name

, Data_Array_Name

, Data_Array_Offset

, Function

, Node_Name

, Address

, Length

, Data_Array_Low_Scale

, Data_Array_High_Scale

, Node_Low_Scale

, Node_High_Scale

SMD_AI_01

, DA_AI_01

, 0

, Passive

, MBP_Srv_13

, 30001

, 200

, 0

, 100

, 0

, 10000

SMD_AO_01

, DA_AO_01

, 0

, Passive

, MBP_Srv_13

, 40001

, 200

, 0

, 100

, 0

, 10000

Map_Descriptors

Map_Descriptor_Name

, Data_Array_Name

, Data_Array_Offset

, Function

, Node_Name

, Address

, Length

, Data_Type

SMD_DO1

, DA_DO_01

, 0

, Passive

, RTU_Srv_21

, 00001

, 1

, Slave_ID

Length is not
used, revert to
default of 1

6.3.3 Map Descriptor Exam pl e s

6.3.4 Slave_Id

The following Map Descriptor is used to respond to the Report Slave_Id request. The FieldServer's Slave_Id is 11 and the run status depends upon the data
validity at the specified offset in the specified Data Array - if the data is valid, the status will be 255 (running) otherwise the status will be 0 (off).

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Map_Descriptors

Map_Descriptor_Name

, Data_Array_Name

, Data_Array_Offset

, Function

, Node_Name

, Address

, Length

, Data_Array_Low_Scale

, Data_Array_High_Scale

, Node_Low_Scale

, Node_High_Scale

SMD_AI1

, DA_AI_01

, 0

, Passive

, MBP_Srv_11

, 30001

, 200

, 0

, 100

, 0

, 10000

SMD_AO1

, DA_AO_01

, 0

, Passive

, MBP_Srv_11

, 40001

, 200

, 0

, 100

, 0

, 10000

Appendix A. Useful Features – Modbus RTU

Appendix A.1. Managing Floating points with Modbus

Modbus as a standard does not support floating point formats. Many vendors have written higher level communications software to use two 16 bit registers
to represent floating point or 32 bit integers. This requires conversion software on both ends of the communication channel. The FieldServer supports this
function and also provides other options to resolve this issue.

Appendix A.1.1. Transferr i ng n o n-integer v a l u e s w ith one register

It is possible to represent values higher than 32767 using one register in one of two ways:

 Declare data arrays as type Uint16 (Unsigned integer). This will give you a range from 0 to 65535.
 Use the scaling function on the FieldServer, which will allow you to set up any range, with 16 bit resolution.

The following example shows how scaling can be achieved on the Server side of the configuration. Note that scaling can also be done on the Client side to
scale down a value that was scaled up by a Modbus vendor. Further information regarding scaling can be found in the FieldServer Configuration manual.

Example :

This example multiplies the values in the data array by 100 (10000 on Node_High_Scale is 100X larger than 100 on Data_Array_High_Scale). This is most
commonly used when the user wants to introduce values after the decimal point. For example, a value of 75.6 will be sent as 7560, which can then be rescaled
by the Modbus master.

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Data_Arrays

Data_Array_Name

, Data_Format

, Data_Array_Length

DA1

, Float

, 20

DA2

, UInt32

, 20

DA3

, Float

, 20

DA4

,UInt32

, 20

// Client Side Map Descriptors

// For Nodes where Address_Type is PDU

Map_Descriptors

Map_Descriptor_Name

, Data_Array_Name

, Data_Array_Offset

, Function

, Node_Name,

, Data_Type

, Address

, Length

,Scan_Interval

CMD_AO_01

, DA1

, 0

, Rdbc

, MODBUS DEVICE2

, Float_Reg

, 0

, 20

,1.000s

CMD_AO_02

, DA2

, 0

, Rdbc

, MODBUS DEVICE2

, 32-Bit_Reg

, 0

, 20

,1.000s

CMD_AI_01

, DA3

, 0

, Rdbc

, MODBUS DEVICE2

, Input_Float

, 0

, 20

,1.000s

CMD_AI_02

, DA4

, 0

, Rdbc

, MODBUS DEVICE2

, Input_Reg_32Bit

, 0

, 20

,1.000s

Appendix A.1.2. Transferr ing 3 2 b it values with two r e g i s t e rs

If a Modbus Server sends two consecutive registers to the FieldServer representing either a floating point value or
a 32 bit integer value, the FieldServer can combine and decode these registers back into their original format. To
do this declare Data Array of type Float or UINT32 and set the Map Descriptor Data_Type as ‘Float_Reg’ or ‘32­Bit_Reg’ etc

Example:

Each Map Descriptor will read 20 pairs of registers and store them as 32-bit floating number or 32-bit Integer.

If somehow server device send swapped registers (low value register first) then use corresponding _swap
data_types.

Note: Please note starting addresses per address_type, see section 5.3.2

Appendix A.2. Node_Offline_Response

This function is specific to the Modbus RTU driver.

In systems where data is being collected from multiple Server Nodes and made available on a FieldServer
configured as a Modbus RTU Server, when a Server Node goes offline the default behavior of the FieldServer
would be to stop responding to polls for this data. This might not be what the user wants. Various options exist
making it possible to signal that the data quality has gone bad without creating error conditions in systems
sensitive to the default option.

The following options can be configured under the Node parameter, Node_Offline_Response, to set the response
of the FieldServer to the Modbus RTU Client when the Server Node supplying the data is offline:

 No_Response - this is the default option. The FieldServer simply does not respond when the

corresponding Server Node is offline.

 Old_Data - The FieldServer will respond, but with the last known value of the data. This maintains the

communication link in an active state, but may hide the fact that the Server Node is offline.

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Nodes

Node_Name

, Node_ID

, Protocol

, Node_Offline_Response

, Port

DEV11

, 11

, Modbus_RTU

, No_Response

, -

DEV12

, 12

, Modbus_RTU

, Old_Data

, -

DEV15

, 15

, Modbus_RTU

, Zero_Data

, -

DEV16

, 16

, Modbus_RTU

, FFFF_Data

, -

DEV17

, 17

, Modbus_RTU

, Exception_4.

, -

DEV18

, 18

, Modbus_RTU

, Gateway_Path_Unavailable

, -

 Zero_Data - The FieldServer will respond, but with the data values set to zero. If the user normally expects

non-zero values, this option will signal the offline condition without disrupting communications.

 FFFF_Data - The FieldServer will respond, but with the data values set to FFFF (hex). If the user normally

expects other values, this option will signal the offline condition without disrupting communications.

When configured as a Server this parameter can force a desired exception response as follows:

 Node_Offline_Message or Exception_4 - FieldServer's response will be Exception 4
 Gateway_Path_Unavailable or Exception_A - FieldServer's response will be Exception A
 Gateway_Device_Failed or Exception_B - FieldServer's response will be Exception B

Example:

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Appendix B. Troubleshooting

Appendix B.1. Server Configuration of System Station Address

When using the FieldServer as a Modbus Server, the FieldServer System Station address must be configured to be
different from any of the configured Modbus Server Node_ID’s. Configuring these to be the same invokes
proprietary system information to be transmitted, and should therefore be avoided.

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Appendix C. Vendor Information

Appendix C.1. Connection to York Modbus Microgateway

If connecting the FieldServer to a York Modbus Microgateway, the Node_ID of the Microgateway is defined by the

address DIP switches. If switch 4 is set to ‘On’ and the other switches are set to ‘off’ then Node_ID of the
Microgateway is ‘247’, the parity is ‘Even’, and the stop bits are 1. Other Node_ID combinations can be found in

the York Modbus Microgateway Installation Manual.

Appendix C.2. Modbus ASCII - Examples of FieldServer setup for typical clients

Appendix C.2.1. FieldServer with GE Cim plicit y a s client

 Run the Cimplicity “Workbench” and create a “New Project” with a unique “Project Name” option of

“Basic Control” and protocol “Modbus ASCII”.

 Check the project properties and continue with the “Project Wizard Setup” that appears.
 Add Modbus port giving it a description.
 Create and configure the devices, select “new item”.
 Name the device, select the port, give it a description (e.g. FieldServer), and choose “SYSTEM” resource.
 Create and configure the points.
 Select “new item”, name the point and choose the appropriate device.
 Under the “General” tab, point properties require a description. Note that the elements must have a

value greater than 8.

 Under the “Device” tab, properties need the appropriate address (e.g. 40001 and also require the leading

0’s), change the update criteria to “On Scan”.

 When the project is configured, run by pressing the “play” button.
 Expect the Cimplicity driver to connect and poll the FieldServer for a range of valid addresses, and then

proceed to poll for just the configured Points.

 From the start menu choose the “Point Control Panel”, select edit and add the project you want to view.

Note, to log on the User name “ADMINISTRATOR” must be supplied

 Use “Modbus ASCII Diagnostics” to connect to host and then read the register.

Appendix C.2.2. FieldServer with Intellut i o n F I X as a client

 Install Intellution FIX, choosing the MB1 Modbus ASCII I/O driver
 Run from Start menu and choose “Intellution Fix”.
 Choose “System Configuration Utility”.
 Modify SCADA, add the MB1 Modbus ASCII I/O driver
 Configure the Modbus ASCII Driver.

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 Device is D11, select 5-digit address, add the FieldServer virtual Node ID to station address
 Set up poll record
 SAVE the configuration.
 Open “Startup”
 Open “Mission Control” from the “Apps” menu and confirm Fix is polling.
 To display the data create a link in Fix draw, add link, data link.
 Give it a tagname, allow data entry, numeric entry and set enable option.
 If tag is not in database, select “Add”, choose “AR”. Then set output enable, device MB1, I/O address d11.
 Save the settings
 Use “Quickview” from the “View” menu to confirm the reading of data without ??? appearing
 Change the value and wait a few seconds to ensure the change really occurred.

.

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Address range

Data_Type

Function Code (Write)

Function Code (Read)

1 - 65536

Coil

15 1 1 – 65536

Discrete_Input

n/a.

2

1 – 65536

Input_Register

n/a.

4

1 - 65536

Holding_Register

16

3

Address range

Data_Type

Function Code (Write)

Function Code (Read)

0 - 65535

FC01

15 1 0 – 65535

FC02

n/a. 2 0 – 65535

FC04

n/a. 4 0 – 65535

FC03

16

3

Address range

Data_Type

Function Code (Write)

Function Code (Read)

00001 - 09999

Coil

5,15

1

10001 - 19999

Discrete_Input

n/a. 2 30001 - 39999

Input_Register

n/a. 4 40001 - 49999

Holding_Register

6,16

3

Appendix D. Reference

Appendix D.1. Data Types

If Node parameter Address_Type is set as ADU or PDU, then Data_Type must be specified as follows

For Address_Type ADU :

For Address_Type PDU :

For Address_Type Modicon_5digit

When a Modbus address range is specified, a particular Data Type is implied. The defaults are as follows:

Appendix D.2. Single Writes

If writing multiple registers the write function will 16

If writing multiple coils the write function will 15

If writing a single register the write function will be 6 unless Write_FNC parameter is set to “Multiple’

If writing a single coil the write function will be 5 unless Write_FNC parameter is set to “Multiple’

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