The Socket Server Connector allows SIA Connect to accept a raw TCP connection from another device or application. Use it to receive unsolicited text, send values to a connected client, or send a request and wait for the client's reply without adding an application-specific protocol.

This guide explains how to create a Socket Server instance, use its automatically created items, configure custom items, verify communication, and resolve common errors.

Before you begin

Prepare the following information:

• An unused TCP port on SIA Connect. The default is 1300.
• The IP address that the client will use to reach SIA Connect.
• The message encoding and delimiter expected by the client.
• Whether the client sends data without a request, receives data from SIA Connect, or replies to a request.

Make sure the client can route to SIA Connect and that firewalls allow inbound TCP connections to the selected port. Each Socket Server instance must use a port that is not already occupied by another service.

Install the Connector

1. In the Edge Portal, open Configuration > Connectors.
2. Find Socket Server TCP/IP.
3. Install the Connector if it is not already installed.

For complete installation and update instructions, see Install and manage Connectors.

Create a Socket Server instance

1. Open Workspace > Instances.
2. Select Add instance.
3. Select Socket Server TCP/IP.
4. Enter a descriptive instance name.
5. Configure the instance parameters.
6. Enable the instance and save it.

When the instance is initialized, the Connector creates three items automatically.

Configure item parameters

The automatically created read and write items can be edited. You can also create a custom read item when the server must send a request before collecting a reply.

The available delimiters are:

Delimiter behavior: TCP is a byte stream and does not preserve application message boundaries. The Connector reads the bytes currently available from the client. It does not wait for the selected delimiter to assemble a complete message. If the received data ends with the selected delimiter, that suffix is removed before the value is published.

Outbound line feed: The Connector adds a line-feed character when it transmits to the client. A request command is sent with that line feed. For a written value, the selected delimiter is added first and the line feed follows it. Configure the client parser with this behavior in mind.

Receive data from a client

1. Open the Socket Server instance and select Items.
2. Edit Read socket.
3. Leave Command empty.
4. Select the delimiter that the client places at the end of its messages.
5. Keep the item event-based and enable it.
6. Save the item.
7. Connect the client to the IP address of SIA Connect and the instance port.
8. Send a test value from the client and confirm that the item receives it.

Event-based reads are forced into the data stream even when the client sends the same value repeatedly. This allows repeated identical messages to be processed as separate events.

A fast burst of TCP data can be combined into one read or split across multiple reads. If exact message framing is required, design the client payload and downstream processing to tolerate TCP chunking.

Send data to a client

1. Edit Write socket.
2. Select the encoding and delimiter expected by the client.
3. Enable and save the item.
4. Create a mapping whose destination is Write socket.
5. Connect the client to the Socket Server instance.
6. Trigger the mapping and confirm that the client receives the value.

If Hex is selected, enter an even-length hexadecimal string such as 0103FF. Do not include spaces or a 0x prefix. The Connector converts the pairs into bytes before transmission.

For mapping instructions, including input templates and triggers, see Create and edit mappings.

Send a request and collect the reply

Create a custom read item when SIA Connect must initiate the exchange.

1. Open the instance and select Add item.
2. Enter a descriptive item name.
3. Set the direction to Read only.
4. Enter the request in Command.
5. Select Plain Text (UTF-8) or Hex.
6. Select the delimiter to remove from the end of the reply.
7. Configure a polling interval instead of event-based reading.
8. Enable and save the item.

When the item runs and a client is connected, the Connector sends the command and waits up to the instance timeout for received data. If no reply arrives, the item reports Timeout waiting for reply from client.

Verify the configuration

1. Confirm that the instance is enabled and has no instance error.
2. Connect a TCP client to a reachable SIA Connect address and the configured port.
3. Confirm that Clients Connected changes from 0 to 1.
4. Send a known message and confirm that Read socket updates.
5. Trigger a controlled write and compare the received bytes on the client with the configured encoding and delimiter.

Troubleshoot the Connector

The client cannot connect

Confirm that the instance is enabled, the client uses TCP, and the destination address belongs to SIA Connect. Check the port number, routing, VLAN configuration, and firewall rules. A successful ping confirms basic IP reachability but does not prove that the TCP port is open.

The instance reports an error binding the socket

The configured port is normally already in use, unavailable, or invalid. Assign an unused TCP port and restart the instance. Make sure another Socket Server instance or service is not using the same address and port combination.

A second client connects but does not exchange data

The current Connector processes one active client session at a time. Disconnect the first client before using another one. Do not design the integration around concurrent clients.

Clients Connected remains 0

The TCP session has not been accepted or has disconnected. Check the client connection state and confirm it is connecting to the correct IP address and port. Review the Connector and system logs for accept, read, or socket errors.

The received value includes unexpected characters

Check the client's terminator and the item's selected delimiter. The selected delimiter is removed only when it appears at the end of the received data. Remember that transmitted data from this Connector includes a final line feed.

Messages are split or combined

TCP does not preserve message boundaries, and the Connector does not buffer data until the selected delimiter arrives. Reduce burst traffic, wait for each exchange to complete, or add downstream parsing that can handle partial and combined payloads.

A request item times out

Confirm that Clients Connected is 1, the command is valid, and the client is programmed to reply. Increase the instance timeout if the client needs more than 2000 ms. Also verify that the client accepts the line feed added to the request.

Hex output is empty or incorrect

Use only hexadecimal characters and provide complete byte pairs. For example, use 010AFF, not 0x01 0A FF. Plain-text values should use Plain Text (UTF-8).

A write produces no data at the client

Confirm that a client is actively connected, the write item is enabled, and the mapping runs. Check the mapping source, trigger, condition, and input template. Then review logs for an invalid socket, socket-state error, or write failure.

The Connector stops receiving after a disconnect

Allow the instance to accept a new session, then reconnect the client. If it does not resume, disable and enable the instance or restart the Connector. Review logs for socket read, select, or listening errors.

For general diagnostics, see Troubleshoot Connector, instance, item, and mapping errors.

Related articles

• Install and manage Connectors
• Create and edit instances
• Create and edit items
• Create and edit mappings
• Troubleshoot Connector, instance, item, and mapping errors
• Socket Server releases