Added example how to read a SDO

examples/read_sdo.rs

@@ -0,0 +1,44 @@
+//! Example: Read an int8 SDO from a slave
+//!
+//! This example demonstrates a simple SDO read of a single signed byte
+//! (int8) from a slave device. It opens the EtherCAT master (index 0) with
+//! read/write access, requests SDO 0x6061 subindex 0 from the first slave
+//! (slave position 0) and prints the interpreted signed value.
+//!
+//! Usage
+//! ```text
+//! # From the workspace root
+//! cargo run --example sdo
+//! ```
+use ethercat::{Master, MasterAccess, SdoIdx, SlavePos};
+
+pub fn main() -> Result<(), std::io::Error> {
+    // Initialize the logger to see info messages from the library.
+    env_logger::init();
+
+    log::info!("Opening EtherCAT master...");
+    // Open the first master (index 0) with read/write access. Adjust the index
+    // if your setup uses a different master interface.
+    let master = Master::open(0, MasterAccess::ReadWrite)?;
+
+    // Read from the first slave (position 0) and SDO index 0x6061, subindex 0.
+    let slave_pos = SlavePos::from(0);
+    let sdo_idx = SdoIdx::new(0x6061, 0);
+
+    // Read an i8 SDO value (1 byte) from the slave
+    log::info!("Reading SDO 0x6061:0 [int8]...");
+    // Create a buffer to hold the data returned by the SDO upload.
+    let mut buf = [0u8; 1];
+    // Perform the read operation (make the slave "upload" the SDO to the master)
+    let data = master.sdo_upload(slave_pos, sdo_idx, false, &mut buf)?;
+    if data.len() >= 1 {
+        // Interpret the single returned byte as a signed 8-bit integer
+        // (two's complement).
+        let val = data[0] as i8;
+        println!("SDO 0x{:X}/{} read int8 = {}", 0x6061, 1, val);
+    } else {
+        println!("SDO read returned {} bytes", data.len());
+    }
+
+    Ok(())
+}