.. _auto_flange_serial_read:

flange_serial_read (Auto Mode)
------------------------------------------
This section explains how to use :ref:`flange_serial_read <flange_serial_read>`  
during **Auto (Run)** operations to receive data from a device connected to the  
robot’s flange-mounted serial port.

This function waits up to the given timeout for data on the given port and returns the received bytes and their count in a FLANGE_SER_RXD_INFO_EX structure, allowing the robot to process responses or sensor readings from the tool.

**Typical usage**

- Receive status feedback from a smart gripper.  
- Read barcode/QR scan data from a serial scanner.  
- Acquire sensor data from tool-mounted measurement devices.  
- Implement handshake/acknowledgment logic with external peripherals.

.. Note::

    - The serial port must be opened beforehand with ``flange_serial_open``.  
    - Many devices require request–response timing considerations.
    - The flange board revision used by the flange serial and flange I/O functions is read at open_connection.

**Example: Reading a Response From a Tool Device**

.. code-block:: cpp

   // Open serial port
   drfl.flange_serial_open(1, 115200);

   // Wait up to 3 seconds for data on port 1 (X1)
   LPFLANGE_SER_RXD_INFO_EX rx = drfl.flange_serial_read(3.0f, 1);

   if (rx == nullptr || rx->_iSize <= 0) {
       printf("No data received.\n");
       return -1;
   }

   printf("Received (%d bytes): %.*s\n", rx->_iSize, rx->_iSize, (const char*)rx->_cRxd);

In this example, data is read from the tool after a previous write operation,  
allowing the robot to receive device responses in Auto mode.

**Tips**

- One read returns at most 256 bytes.
- Some devices require a delay after write before attempting to read.  
- Use polling or loop-based reads for larger or streaming data.  
- Combine with serial-write to implement command–response or handshake protocols.