Certificates

If a Modbus server uses TLS, place client and server certificates in the adapter component's Certificates directory:

• Windows: C:\ProgramData\OSIsoft\Adapters\Modbus\Certificates

• Linux: /usr/share/OSIsoft/Adapters/Modbus/Certificates

The Certificates directory secures certificate files using Access Control Lists (ACLs). Special permissions configured by the adapter provide an additional security layer for the certificates within the directory.

Certificates placed here can then be referenced by filename in the Data Source configuration for the component. Subpaths can be specified in the configuration if you place files in subdirectories within the Certificates directory.

Alternatively, specify the full path to a certificate stored in another location. When you use this option, you are responsible for securing the certificate. Ensure that the certificate files have the appropriate permissions for access by the adapter process.

Example certificate entries in data source configuration

Files placed in adapter certificates directory

{

"Devices": [

{

"id": "TLS_Device1",

"ipAddress": "127.0.0.1",

"port": 802,

"minTlsVersion": "1.3",

"serverCertificate": "ca_cert.pem",

"serverCertificateDnsName": "aveva.com"

}

],

"ClientCertificate": "client_cert.pem",

"ClientPrivateKey": "client_key.pem"

}

Files placed in subdirectories of adapter certificates directory

{

"Devices": [

{

"id": "TLS_Device1",

"ipAddress": "127.0.0.1",

"port": 802,

"minTlsVersion": "1.3",

"serverCertificate": "RootCA\ca_cert.pem",

"serverCertificateDnsName": "aveva.com"

}

],

"ClientCertificate": "Client\client_cert.pem",

"ClientPrivateKey": "Client\client_key.pem"

}

Absolute paths to certificate files

{

"Devices": [

{

"id": "TLS_Device1",

"ipAddress": "127.0.0.1",

"port": 802,

"minTlsVersion": "1.3",

"serverCertificate": "C:\Certs\RootCA\ca_cert.pem",

"serverCertificateDnsName": "aveva.com"

}

],

"ClientCertificate": "C:\Certs\Client\client_cert.pem",

"ClientPrivateKey": "C:\Certs\Client\client_key.pem"

}