The Socket Client Connector opens an outbound TCP connection from SIA Connect to a socket server. Use it to send commands, receive delimited messages, perform request-and-reply communication, or send mapped values to a TCP service.

The Connector supports plain TCP, TLS server verification, and mutual TLS. Messages can be sent as UTF-8 text or decoded from hexadecimal input.

Before you begin

• Install the Socket Client TCP/IP Connector. See Install and manage Connectors.
• Obtain the server's hostname or IP address and TCP port.
• Allow SIA Connect to reach the server through the required network and firewall rules.
• Confirm whether the connection uses plain TCP, TLS, or mutual TLS.
• Confirm the message encoding and delimiter expected by the server.
• For request-and-reply communication, obtain the command that requests the required value.
• For TLS, upload the required certificates and keys before creating the instance.

Choose the communication pattern

The Connector keeps one connection for each instance and reuses it across reads and writes. It removes the connection after a communication failure and reconnects on the next operation.

Upload TLS files

Skip this section when the server uses plain TCP.

1. Open the file management page for the Socket Client Connector.
2. Upload each required PEM file.
3. Assign the matching category to each file:
   • Certificate: Client certificate.
   • Key: Client private key.
   • Root CA: Certificate authority used to verify the server.
   • Certificate chain: Optional intermediate client certificates sent during mutual TLS.
4. Save the files.

See Manage and configure Connector files and certificates for the complete file-management procedure.

Create a Socket Client instance

The Connector does not support instance or item discovery. Configure the connection manually.

1. In the sidebar, expand Workspace and select Instances.
2. Select Create instance.
3. Select the Socket Client TCP/IP Connector.
4. Enter a unique name for the instance.
5. Enter the server's hostname or IP address in Address.
6. Configure the instance parameters described below.
7. Create the instance.

Configure TLS

The selected certificate fields determine whether the Connector uses TLS:

The Connector requires TLS 1.2 or later and verifies the server certificate whenever TLS is enabled.

Use the default items

When an instance is created, the Connector adds two enabled items automatically:

• Read socket: A read-only item for receiving messages or sending a request and receiving its reply.
• Write socket: A write-only item for sending mapped values or fixed commands.

Both default items use Plain Text (UTF-8) encoding and Carriage Return + Line Feed as the delimiter. Edit them to match the server protocol.

You can create additional items when the same server connection uses different commands or message formats.

Configure an item

Select the encoding

Do not add 0x, spaces, or separators to a Hex value unless the server protocol explicitly expects those characters after decoding.

Select the delimiter

For a read item, select the exact delimiter sent at the end of the server response. The Connector waits until the collected data ends with that delimiter, then removes it from the stored value.

None can be used for write-only communication when the server expects no trailing delimiter.

Receive unsolicited messages

1. Open the Read socket item.
2. Leave Command empty.
3. Select the server's encoding and delimiter.
4. Set the required update interval.
5. Save and enable the item.

During each read, the Connector waits for data until Timeout expires. When no command was sent, a timeout is cleared and the connection remains available for the next poll.

The Connector forces each successful reply to be processed, even when it is identical to the previous value.

Send a command and read the reply

1. Open the Read socket item.
2. Enter the request in Command.
3. Select the encoding used by the command.
4. Select the delimiter used for both the outgoing request and incoming reply.
5. Set the required update interval.
6. Save and enable the item.

The Connector appends the delimiter to the command, sends it, and waits for the reply. If the reply is not completed before Timeout, the item reports an error and the connection is closed.

Send values to the socket server

1. Open the Write socket item.
2. Select the required encoding and delimiter.
3. Leave Command empty when a mapping supplies the message.
4. Save and enable the item.
5. Create a mapping from the source item to the Write socket item.
6. Add a template or transformation when the server requires a specific message structure.
7. Enable the mapping and generate a new source value.

The Connector sends the mapped value when it is not empty. If the value is empty, it sends Command instead.

See Create and edit mappings for the complete mapping procedure.

Verify the configuration

1. Enable the Socket Client instance and required items.
2. Confirm that the instance establishes a connection without an error.
3. For a read item, send or request a message that ends with the configured delimiter.
4. Confirm that the received value appears without the trailing delimiter.
5. For a write item, trigger its mapping and confirm that the server receives the expected bytes.
6. For TLS, confirm that the server certificate is accepted and mutual authentication succeeds when configured.

Troubleshoot the Socket Client Connector

If a problem continues, see Troubleshoot Connector, instance, item, and mapping errors.

Related articles

• Install and manage Connectors
• Manage and configure Connector files and certificates
• Create and edit instances
• Create and edit items
• Create and edit mappings
• Troubleshoot Connector, instance, item, and mapping errors
• Socket Client releases