SMC Networks FieldServer Driver Manual

FieldServer

FS-8704-15 XML over HTTP Driver

Driver Manual

(Supplement to the FieldServer Instruction Manual)

APPLICABILITY & EFFECTIVITY

Effective for all systems manufactured after October 2017.

Driver Revision: 1.15

Document Revision: 2.E

XML over HTTP Driver Manual

Contact Information

Technical Support

Please call us for any technical support needs related to the FieldServer product.

Sierra Monitor Corporation
1991 Tarob Court
Milpitas, CA 95035

Website: www.sierramonitor.com

U.S. Support Information:

[phone]
[phone]

Email: [e-mail]

EMEA Support Information:

[phone]

Email: [e-mail]

XML over HTTP Driver Manual

Table of Contents

TABLE OF CONTENTS

HTTP XML Driver Description ............................................................................................................. 4

Driver Scope of Supply ....................................................................................................................... 4

2.1 Supplied by Sierra Monitor for this Driver ....................................................................................... 4

Hardware Connections ........................................................................................................................ 5

Data Array Parameters ........................................................................................................................ 6

Configuring the FieldServer as a HTTP XML Driver Client .............................................................. 7

5.1 Client Side Connection Parameters ............................................................................................... 7

5.2 Client Side Node Parameters ......................................................................................................... 8

5.3 Client Side Map Descriptor Parameters ......................................................................................... 9

5.3.1 FieldServer Specific Map Descriptor Parameters ................................................................... 9

5.3.2 Driver Related Map Descriptor Parameters ............................................................................ 9

5.3.3 Timing Parameters ................................................................................................................ 10

5.3.4 Special Keywords for URL and Write_Command ................................................................. 10

5.4 Map Descriptor Examples ............................................................................................................ 10

Configuring the FieldServer as a HTTP XML Driver Server .......................................................... 11

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

6.2 Server Side Node Parameters ...................................................................................................... 11

6.3 Server Side Map Descriptor Parameters ...................................................................................... 11

6.4 Server Side Requests and Responses Supported ....................................................................... 12

Appendix A. XML Server Schema ........................................................................................................... 13

Appendix B. Status Parameter BITS Table ............................................................................................. 14

Appendix C. Setting the Format of the Data Array Age ........................................................................ 15

Appendix D. Use of SSl/TLS for Secture Connection ........................................................................... 16

Appendix D.1. Configuring FieldServer as a SSL/TLS Server ................................................................ 16

Appendix D.1.1. Simple Secure Server Configuration......................................................................... 16

Appendix D.1.2. Limiting Client Access ............................................................................................... 17

Appendix D.1.3. To Upload the Authority File to the FieldServer ........................................................ 17

Appendix D.1.4. Certificate Validation Options .................................................................................... 18

Appendix D.1.5. Certificate Validation Options .................................................................................... 18

Appendix D.2. Configuring FieldServer as SSL/TLS Client .................................................................... 19

Appendix D.2.1. Simple Secure Client Configuration .......................................................................... 19

Appendix D.2.1. Limit Server Access .................................................................................................. 19

Appendix D.2.2. Certificate Validation Options .................................................................................... 19

Appendix D.2.3. Set up Client Certificate ............................................................................................ 19

XML over HTTP Driver Manual

Page 4 of 19

HTTP XML DRIVER DESCRIPTION

The Ethernet HTTP XML Driver allows the FieldServer to transfer data to and from a device over Ethernet
using the HTTP/XML Driver protocol. The FieldServer can emulate either a server or client.

The XML Driver is built on HTTP web technology (Port 80) and uses pages formatted in XML syntax to
respond to HTTP requests or allows XML responses to be decoded and stored. Both a client and a server
are supported.

The Server Side is an XML formatted response of the internal Data Array structure contained within the
FieldServer, requested from a remote client device to the FieldServer URL.

The Client Side uses a HTTP GET request to a specified URL to request XML data. The driver has the
ability to decode the XML response and store different Elements uniquely identified by some attribute
within the element. The data of the matching Element is stored in the FieldServer Data Arrays the
matching Element is stored in the FieldServer Data Arrays.

FieldServer Mode

Comments

Server

This mode is always enabled within the XML driver, and is requested by “http://<ip

address>/data_arrays.xml” where <ip address> corresponds to the FieldServer IP

Address.

Client

Supports multiple client connections to different URLs, with associated decoding
map descriptors linked to an active GET URL request.

Max Nodes Supported

FieldServer Mode

Nodes

Comments

Client

32

The Driver can establish a connection to several different IP
Addresses.

Server

0

The Server Side is always enabled and defined on the
connection; hence the driver does not allow any server node
selection.

DRIVER SCOPE OF SUPPLY

2.1 Supplied by Sierra Monitor for this Driver

PART #

Description

FS-8915-10

UTP cable (7 foot) for Ethernet connection

XML over HTTP Driver Manual

Page 5 of 19

HARDWARE CONNECTIONS

The FieldServer is connected to the network as shown in connection drawing.

FieldServer

FieldServer Part #

8915-10

UTP cable

Connect to an Ethernet Port

on the FieldServer

N1

19

Switch/Router

WAN / LAN

Network

The Ethernet connection can be achieved using a switch or crossover cable. The driver will support all
Ethernet connections on a local area network (LAN) or wide area network (WAN) including internet
connections and crossover cable connections.

XML over HTTP Driver Manual

Page 6 of 19

DATA ARRAY 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.

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, Uint32, Sint32,
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

Example

// Data Arrays

Data_Arrays

Data_Array_Name

, Data_Array_Format

, Data_Array_Length

DA_AI_01

, Float

, 200

DA_AO_01

, Float

, 200

DA_DI_01

, Bit

, 200

DA_DO_01

, Bit

, 200

XML over HTTP Driver Manual

Page 7 of 19

CONFIGURING THE FIELDSERVER AS A HTTP XML DRIVER CLIENT

For detailed information on FieldServer configuration, 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 an XML server running over a web server on port 80.

The configuration file tells the FieldServer about its target XML data, and the decoding of data required. In
order to enable the FieldServer as an XML client, the driver independent FieldServer buffers need to be

declared in the “Data Arrays” section, the destination XML servers IP Addresses need to be declared in

the “Client Side Nodes” section, and the data required from the XML requests needs to be mapped in the

“Client Side Map Descriptors” section. Details on how to do this can be found below.

NOTE: In the tables below, * indicates an optional parameter, with the bold legal value being the

default.

5.1 Client Side Connection Parameters

Section Title

Connections

Column Title

Function

Legal Values

Connection

Connection Name.

N1, N21

Protocol

Specify protocol used.

XML-HTTP, HTTP, XML

Example

// Client Side Connections

Connections

Connection

, Protocol

N1

, XML

1

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

available on specific hardware.

XML over HTTP Driver Manual

Page 8 of 19

5.2 Client Side Node Parameters

Section Title

Nodes

Column Title

Function

Legal Values

Node_Name

Provide name for Node.

Up to 32 alphanumeric
characters.

IP_Address

Destination IP Address.

xxx.xxx.xxx.xxx

Host_Name*

Specify the host name of the remote device. If
the Host_Name is used in place of an
IP_Address, the FieldServer will attempt to
resolve the IP_Address before polling remote
device. If both IP_Address and Host_Name are
used, the FieldServer will attempt to resolve the
host name to get the latest IP_Address to use.
Otherwise the configured IP_Address will be
used. The FieldServer will try to resolve the host
name again before starting the node recovery
process to get latest IP_Address. If the host
name can't be resolved, the last known
IP_address is used.

Any valid host name.

Response_End_Time*

Specify time duration in seconds that must
elapse before a response is complete. This
parameter is useful while communicating to a
server that sends responses in chunks and there
is a large delay ( > 2s) between chunks.

1-65535; 2

Protocol

Specify Protocol used.

XML-HTTP, HTTP, XML

Connection

Specify which network adapter to use.

N1, N22

Remote_Node_IP_Port*

Specify port to listen to by the remote server.

0-65535; 80

HTTP_Username*

The credentials the FieldServer must use when
communicating to the HTTP server. Only basic
authentication is supported.

Any alphanumeric string.
HTTP_Password*

Example

// Client Side Nodes

Nodes

Node_Name

, IP_Address

, Protocol

, Connection

, Remote_Node_IP_Port

FS_WEB_01

, 192.168.1.10

, XML

, N1

, 300

2

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

available on specific hardware.

XML over HTTP Driver Manual

Page 9 of 19

5.3 Client Side Map Descriptor Parameters

5.3.1 FieldServer Specific Map Descriptor Parameters

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.

Rdbc, Wrbc, Wrbx, Passive_Client

5.3.2 Driver Related Map Descriptor Parameters

Column Title

Function

Legal Values

Node_Name

Name of Node to fetch data from.

One of the Node names
specified in Section 5.2.

Length

Length of Map Descriptor, Number of
Elements to store into data arrays - this
needs to be separated by some non­numeric character, e.g. space or comma.

Any integer.
Method*

HTTP Fetch Method for active Map
descriptors.

GET, POST

XML-URL

HTTP URL - this does not include the IP.

Up to 200 alphanumeric
characters.

Write_Command*

When using POST method this is the
payload of the data sent to the address.

Up to 200 alphanumeric
characters (special parameters
outlined in Section 5.3.4
allowed).

Linked_Map_Descriptor

This is the active mapdescriptor
responsible for fetching the XML data.

Up to 32 alphanumeric
characters.

Element*

XML Element to store from the XML
response. The syntax is as follows

“Elment.Child Element. Grand Child
Element.Attribute” If the attribute is left

out, the driver stores the Element
contents. If left out, the driver stores the
Data of the furthest child of the matching
element.

Up to 200 alphanumeric
characters.
Search_Value*

String search value to uniquely match the
Element the driver want to store, this could
be any Attribute of the XML response. If
left out, the driver uses the first element to
store the data.

Up to 200 alphanumeric
characters.
Search_Element*

Used to specify which Element the driver
searches for a match.

Up to 200 alphanumeric
characters.

Search_Attribute*

Used to specify which Attribute the driver
searches for a match.

Up to 200 alphanumeric
characters.

HTTP_RESP_DA

This data array stores the HTML response
from a remote device after a Write.

Up to 32 alphanumeric
characters.

XML over HTTP Driver Manual

Page 10 of 19

5.3.3 Timing Parameters

Column Title

Function

Legal Values

Scan_Interval

Rate at which data is polled.

≥0.001s

5.3.4 Special Keywords for URL and Write_Command

Parameter

Description

<DATA_ARRAY_NAME.OFFSET>

Substitute entry with value as float from matching data array and
offset.

<DATA_ARRAY_NAME.OFFSET.C>

Substitute entry with value as ASCII character from matching
data array and offset. Useful for embedding special characters
like < > or " etc.

<local>

Substitute value with Map descriptors first data array entry, or
data offset from match cache block write.

<offset>

Used for passive map descriptors to indicate which offset
changed when the cache block gets created.

5.4 Map Descriptor Examples

// Client Side Map Descriptors

Map_Descriptors

Map_Descriptor_Name

, Function

, Data_Array_Name

, Data_Array_Index

, Node_Name

, Length

CMD_DA_GET1

, RDBC

, DA_HTTP_STR1

, 0

, FS_WEB_01

, 500 , Scan_Interval

, XML-URL

, Method

, 0

, DATA_ARRAYS.XML

, GET

Map_Descriptors

Map_Descriptor_Name

, Function

, Data_Array_Name

, Data_Array_Index

, Node_Name

CMD_RD_UINT16

, PASSIVE_CLIENT

, DA_UINT16

, 0

, FS_WEB_01

, Length

, Linked_Map_Descriptor

, 100

,CMD_DA_GET1

Map_Descriptors

Map_Descriptor_Name

, Element

, Search_Value

, Search_Attribute

CMD_RD_UINT16

, DATA_ARRAYS.DATA_ARRAY.DATA

, DA_AI_01

, name

, Method

, XML-URL

, Write_Command

, POST

, post.cgi

, DA_UINT16.<offset>=<local>

// Write section

Map_Descriptors

Map_Descriptor_Name

, Function

, Data_Array_Name

, Data_Array_Index

, Node_Name

, Length

, Scan_Interval

CMD_WR_UINT16a

, WRBC

, DA_UINT16_WR

, 0

, FS_WEB_01

, 10

, 2s

...

, Method

, XML-URL

, Write_Command

...

, POST

, post.cgi

, "DA_UINT16.0=<DA_UINT16_WR.0>&DA_UINT16.1=<DA_UINT16_WR.1>"

URL and payload of a regular POST command
generated by the FieldServer.

Linked Map Descriptors are also
where the XML request is stored.

Primary read map descriptor with URL. And
method is a GET. HTTP response is stored to the
data array. This is mainly for diagnostic purposes.

XML Element to store, search value to
match on, and XML attribute to match.

If the data changes, do a POST to the following URL with the payload.

XML over HTTP Driver Manual

Page 11 of 19

CONFIGURING THE FIELDSERVER AS A HTTP XML DRIVER SERVER

For detailed information on FieldServer configuration, 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 an XML client. This can be any web browser such as Internet Explorer or Firefox. Or
this can be any other XML client application.

NOTE: In the tables below, * indicates an optional parameter with the bold legal value being the

default.

6.1 Server Side Connection Parameters

Section Title

Connections

Column Title

Function

Legal Values

Connection

Connection Name

N1 / N2

Protocol

Specify protocol used

XML-HTTP, HTTP, XML

IP_Port

To specify on which port the HTTP driver listens as a
server.

0-65535, 80
Max_Sessions*

Specify the maximum number of sessions.

Any integer value; 100

Example

// Server Side Connections

Connections

Connection

, Protocol

N1

, XML

6.2 Server Side Node Parameters

Nodes do not apply to the server side of this protocol.

6.3 Server Side Map Descriptor Parameters

Map descriptors do not apply to the server side of this protocol.

XML over HTTP Driver Manual

Page 12 of 19

6.4 Server Side Requests and Responses Supported

Request:

http://192.168.1.5/data_arrays.xml

Response:

Section Title

Optional Selective
Data_Array.xml parameters

Parameter

Function

Legal Values

?name=DA_NAME

Specify which Data array to retrieve.

Up to 15 alphanumeric
characters.

:LENGTH

Number of values to return.

>=1

.OFFSET

Start at which offset in the Data Array.

>=0

&name= …

Add another Data Array to the
response. When adding additional
Data Arrays, Length and Offset
parameters must also be included.

Up to 15 alphanumeric
characters.

STATUS

Validity status of data. See Appendix

B for BITS table.

2 = Invalid
272 = Valid, Waiting
400 = Valid, Waiting, Offline
912 = Valid, Waiting, Offline

and Old

Example

http://192.168.1.5/data_arrays.xml?name=DA_REG01.01:5&name=DA_REG02.01:5

<DATA_ARRAYS FST_XML_VERSION="1.00" MAX_INDEX="5" BRIDGE_TITLE="Lonworks Server">

<DATA_ARRAY NAME="DA_Group" FORMAT="Byte" LENGTH="99" INDEX="1">

<DATA OFFSET="0" DATA_AGE="3:00:39:36.736s" STATUS="0">0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0</DATA>

</DATA_ARRAY>
<DATA_ARRAY NAME="DA_P16_1Sta" FORMAT="Byte" LENGTH="2" INDEX="2">

<DATA OFFSET="0" DATA_AGE="34.705s" STATUS="0">0 0</DATA>

</DATA_ARRAY>
<DATA_ARRAY NAME="DA_Pnl16_1" FORMAT="Byte" LENGTH="8" INDEX="3">

<DATA OFFSET="0" DATA_AGE="3:00:39:36.646s" STATUS="0">0 0 0 1 0 0 0 0</DATA>

</DATA_ARRAY>
<DATA_ARRAY NAME="DA_P16_2Sta" FORMAT="Byte" LENGTH="2" INDEX="4">

<DATA OFFSET="0" DATA_AGE="34.050s" STATUS="0">0 0</DATA>

</DATA_ARRAY>
<DATA_ARRAY NAME="DA_Pnl16_2" FORMAT="Byte" LENGTH="8" INDEX="5">

<DATA OFFSET="0" DATA_AGE="3:00:39:36.548s" STATUS="0">1 0 0 0 0 0 0 0</DATA>

</DATA_ARRAY>

</DATA_ARRAYS>

XML over HTTP Driver Manual

Page 13 of 19

APPENDIX A. XML SERVER SCHEMA

Below is the XML schema used for server responses to the data_Arrays.xml request.

<xs:schema elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="DATA_ARRYS">
<xs:attribute name="FST_XML_VERSION" type="xs:string" />
<xs:attribute name="MAX_INDEX" type="xs:string" />
<xs:attribute name="BRIDGE_TITLE" type="xs:string" />
<xs:complexType>
<xs:sequence>
<xs:element name="DATA_ARAY">
<xs:attribute name="NAME" type="xs:string" />
<xs:attribute name="FORMAT" type="xs:string" />
<xs:attribute name="LENGTH" type="xs:string" />
<xs:attribute name="INDEX" type="xs:string" />
<xs:complexType>
<xs:element name="Data" type="xs:string">
<xs:attribute name="OFFSET" type="xs:string" />
<xs:attribute name="DATA_AGE" type="xs:string" />
<xs:attribute name="STATUS" type="xs:string" />
</xs:element>
</xs:complexType>
</xs:element>
</xs:complexType>
</xs:element>
</xs:schema>

XML over HTTP Driver Manual

Page 14 of 19

APPENDIX B. STATUS PARAMETER BITS TABLE

Data Status

Hex Value

Description

DATA_BAD

0x0002

Data considered invalid due to one or multiple reasons.
For example: a bad sensor, out of range analog input,
trouble, reliability, etc.

DATA_VALID

0x0010

Data valid

DATA_COPIED

0x0020

Copy of data made

DATA_FNC_AFTER_STORE

0x0040

Function after store required on this data array.

DATA_OFFLINE

0x0080

Offline

DATA_WAITING

0x0100

Waiting

DATA_OLD

0x0200

Old

DATA_EXPIRED

0x0400

Expired

DATA_STARTUP

0x0800

Startup

DATA_UNRELIABLE

0x1000

Data Reliability

XML over HTTP Driver Manual

Page 15 of 19

APPENDIX C. SETTING THE FORMAT OF THE DATA ARRAY AGE

By default the data age of a data array starts at 'S.SSS' and grows to 'M:SS.SSS', 'H:MM:SS.SSS' or
'D:HH:MM:SS.SSS' accordingly. The Disp_Time_Format defines if the time format follows H:MM:SS.SSS
or D:HH:MM:SS.SSS.

Section Title

Bridge

Parameter

Function

Legal Values

Title

Allows user to specify the title of the FieldServer.

Title Text

Disp_Time_Format

Time format of the data array age.

HH:MM:SS.SSS,

D:HH:MM:SS.SSS

Example

//================================================================================
//
// Common Information
//

Bridge
Title , Disp_Time_Format
HTTP WEB/XML Server , HH:MM:SS.SSS

XML over HTTP Driver Manual

Page 16 of 19

APPENDIX D. USE OF SSL/TLS FOR SECTURE CONNECTION

SSL/TLS (Secure Sockets Layer/Transport Layer Security) is a security technology for establishing an
encrypted connection between a server and a client. This allows the secure transfer of data across
untrusted networks.

These functions are supported on the following:

FS-QS-1010 or FS-QS-1210 with a serial number starting with 14 or later (indicating the year it shipped).
FS-QS-1011 or FS-QS-1211 with a serial number starting with 15 or later (indicating the year it shipped).

Minimum BIOS requirement: 2.6.1

Appendix D.1. Configuring FieldServer as a SSL/TLS Server

The following example sets the FieldServer to accept a secure Modbus/TCP connection on port 1502.

Appendix D.1.1. Simple Secure Server Configuration

Add TLS_Port parameter in the connections section of the configuration file and set to a port number
between 1 – 65535.

Connections
Adapter , Protocol , TLS_Port
N1 , Modbus/TCP , 1502

This configuration sets the FieldServer to accept any incoming connection but will not request a client’s

certificate for verification. This means that the FieldServer end point communication will be encrypted but
not authenticated.

The FieldServer will send an embedded self-signed certificate if one is requested by a connecting client.

NOTE: If a remote client requires a certificate, then request the smc_cert.pem certificate from

Sierra Monitor Technical Support and update the remote client’s authority as per vendor
instructions.

XML over HTTP Driver Manual

Page 17 of 19

Appendix D.1.2. Limiting Client Access

In addition to TLS_Port parameter also add Validate_Client_Cert in the connections section of the
configuration file and set it to “Yes”.

Connections
Adapter , Protocol , TLS_Port , Validate_Client_Cert
N1 , Modbus/TCP , 1502 , Yes

The configuration above sets the FieldServer to request and verify a client’s certificate against its internal
authority file before accepting connection. By default, this means the FieldServer will only accept
connections from other FieldServers.

In order to load an authority file so that the FieldServer will accept connections from a chosen list of
remote clients, configure the FieldServer with the following connection settings:

Connections
Adapter , Protocol , TLS_Port , Validate_Client_Cert , Cert_Authority_File
N1 , Modbus/TCP , 1502 , Yes , my_authorized_clients.pem

This configuration has the FieldServer accept connections from clients who have the correct certificate.
The authority file is a collection of client certificates in PEM format. This file can be edited using any text
file editor.

NOTE: Cert_Authority_File is useful only if Validate_Client_Cert is set to ‘Yes’.

Appendix D.1.3. To Upload the Authority File to the FieldServer

• Enter the IP address of the FieldServer into a web browser.

• Choose the ‘Setup’ option in the Navigation Tree and Select ‘File Transfer’.

• Choose the ‘General’ tab.

• Click on the ‘Browse’ button and select the PEM file you want to upload.

• Click on ‘Submit’.

• When it says “The file was uploaded successfully”, click on the ‘System Restart’ button.

XML over HTTP Driver Manual

Page 18 of 19

Appendix D.1.4. Certificate Validation Options

If connections must be limited to only a particular domain (vendor devices), include Check_Remote_Host
to specify the domain/host name.

Connections
Adapter , Protocol , TLS_Port , Validate_Client_Cert , Cert_Authority_File , Check_Remote_Host
N1 , Modbus/TCP , 1502 , Yes , my_authorized_clients.pem , SMC

The configuration above tells the FieldServer to only accept connections that have the correct certification
and is coming from the specified host.

The Check_Remote_Host value is synonymously known as common name, host name or domain etc.
The common name can be obtained by the following methods:

• Ask the certificate issuer for the host name.

• Use online tools to decode the certificate (for example: https://www.sslshopper.com/certificate-

decoder.html).

• If the program openssl is installed on the local PC, then run the following command to get the
common name: openssl x509 -in certificate.pem -text -noout

Appendix D.1.5. Certificate Validation Options

Make sure the certificate is in PEM format. Otherwise, convert it to PEM format (reference the link below).

support.ssl.com/Knowledgebase/Article

Configure the FieldServer to use a custom certificate as shown below:

Connections
Adapter , Protocol , TLS_Port , Server_Cert_File
N1 , Modbus/TCP , 1502 , my_server_cert.pem

XML over HTTP Driver Manual

Page 19 of 19

Appendix D.2. Configuring FieldServer as SSL/TLS Client

The following Node configurations set the FieldServer to open a secure Modbus/TCP connection to the
server at IP Address 10.11.12.13 on port 1502.

Appendix D.2.1. Simple Secure Client Configuration

Add Remote_Node_TLS_Port parameter in the nodes section of the configuration file and set to a port
number between 1 – 65535.

Nodes
Node_Name , Node_ID , Protocol , Adapter , IP_Address , Remote_Node_TLS_Port
PLC_11 , 11 , Modbus/TCP , N1 , 10.11.12.13 , 1502

The above configuration sets the FieldServer to connect to a remote server but does not request a
server’s certificate for verification. This means that the FieldServer end point communication will be
encrypted but not authenticated.

If requested by a remote server, the FieldServer will send an embedded self-signed certificate.

Appendix D.2.1. Limit Server Access

Add the Validate_Server_Cert parameter to the client node section of the configuration.

……. , Remote_Node_TLS_Port , Validate_Server_Cert
…….. , 1502 , Yes

The above configuration sets the FieldServer to request and verify the server’s certificate against its own
internal authority file before finalizing the connection. By default, this means the FieldServer will only
establish connections to other FieldServers.

……. , Remote_Node_TLS_Port , Validate_Server_Cert , Cert_Authority_File
…….. , 1502 , Yes , my_authorized_servers.pem

The above configuration sets the FieldServer to use a specified PEM file to allow custom server
connections.

The authority file is a collection of server certificates in PEM format. This file can be edited using any text
file editor (such as notepad). When the file has all required certificates, paste it into the PEM formatted
server certificate. Now the FieldServer will connect to a server if it can find the server’s certificate in the
authority file.

NOTE: Cert_Authority_File is useful only if Validate_Client_Cert is set to ‘Yes’.

To upload the Certificate to the FieldServer follow the directions for the authority file in Appendix D.1.3.

Appendix D.2.2. Certificate Validation Options

Use the Check_Remote_Host element as described in Appendix D.1.4.

Appendix D.2.3. Set up Client Certificate

Make sure the certificate is in PEM format. Otherwise, convert it to PEM format (reference the link below).

support.ssl.com/Knowledgebase/Article

Configure the FieldServer to use a custom certificate as shown below:

……… , Client_Cert_File
……… , my_client_cert.pem