> For the complete documentation index, see [llms.txt](https://docs.augelab.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.augelab.com/function-blocks/blocks-reference/input-output/communication/serial-connect.md).
# Serial Connect
This function block opens and manages a serial (COM) connection. Use it to connect to serial devices, monitor connection state, and expose a connection identifier for other blocks to reference.
## đĨ Inputs
This function block does not have any inputs.
## đ¤ Outputs
`ConnId` Unique identifier for the opened serial connection. Use this value to reference the connection from other blocks.
`Connected?` Boolean flag that indicates whether the serial connection is currently active.
## đšī¸ Controls
`Port` COM port name to connect to (for example COM3).
`Baud` Communication speed (for example 115200).
`Read timeout (s)` Time in seconds to wait for read operations.
`Line delimiter` Select the line ending used by your device (LF / CRLF / CR).
`AutoReconnect` Switch that enables automatic reconnection when the connection drops.
`Reconnect interval (s)` Interval between reconnection attempts when auto-reconnect is enabled.
`Idle disconnect (s)` Time of inactivity after which the connection will be closed automatically to free the port.
## đ¨ Features
* Automatic connection management: opens a connection with the configured parameters and keeps the `ConnId` available to other blocks.
* Auto-reconnect: optionally retries when the device becomes unavailable.
* Idle disconnect: closes the port when unused to avoid locking the device for other applications.
* Human-readable settings: select newline convention and tune timeouts to match the connected device.
## đ Usage Instructions
1. Set the `Port` and `Baud` values to match your device.
2. Configure `Read timeout (s)` and `Line delimiter` according to your device protocol.
3. Toggle `AutoReconnect` and set `Reconnect interval (s)` if you want the block to recover from disconnections automatically.
4. Adjust `Idle disconnect (s)` to let the block close the port when not in use.
5. Run the scenario. The block will open the connection and output `ConnId` and `Connected?`. Use the `ConnId` in other communication blocks that accept a connection reference.
## đ Evaluation
When evaluated, the block ensures a serial connection exists with the current settings. If settings change, the previous connection is released and a new one is created. The outputs reflect the active connection id and whether the connection is currently established.
## đĄ Tips and Tricks
* Use `Led Output` to visually reflect the `Connected?` state in your UI.
* Use `String Input` or `Number Input` and `String Merge` to craft commands to send over the serial link.
* Use `Data Write Global` / `Data Read Global` to share the `ConnId` or serial results with other parts of your scenario without direct wiring.
* Feed serial data into `Data to JSON` or `CSV Export` to log communication for later analysis.
* Forward parsed data to remote systems with `MQTT Publish` or `REST API - Post` for cloud integration or monitoring.
* Use `Debug Input` to inspect messages while developing your serial workflow.
* Combine with `Send Mail` to trigger email alerts when connection drops or when specific messages arrive.
## đ ī¸ Troubleshooting
* If `Connected?` remains false: verify the device port and baud settings match the device; check device drivers and OS device manager.
* If you cannot open the port: make sure no other application is using the same COM port. Close other programs or enable idle disconnect in those systems.
* If lines appear truncated or merged: try a different `Line delimiter` setting or increase `Read timeout (s)`.
* If frequent disconnects occur: enable `AutoReconnect` and increase `Reconnect interval (s)` to give the device time to recover.
* If unexpected characters appear: confirm baud rate and parity settings with the device documentation and adjust accordingly.