Throw ModbusCrcException on CRC mismatch

Author: kevinherron

modbus/src/main/java/com/digitalpetri/modbus/client/ModbusRtuClient.java

@@ -3,6 +3,7 @@
 import com.digitalpetri.modbus.Crc16;
 import com.digitalpetri.modbus.ModbusRtuFrame;
 import com.digitalpetri.modbus.TimeoutScheduler.TimeoutHandle;
+import com.digitalpetri.modbus.exceptions.ModbusCrcException;
 import com.digitalpetri.modbus.exceptions.ModbusException;
 import com.digitalpetri.modbus.exceptions.ModbusExecutionException;
 import com.digitalpetri.modbus.exceptions.ModbusResponseException;
@@ -169,7 +170,7 @@ private void onFrameReceived(ModbusRtuFrame frame) {
       if (!verifyCrc16(frame)) {
         transport.resetFrameParser();
 
-        promise.future.completeExceptionally(new ModbusException("CRC mismatch"));
+        promise.future.completeExceptionally(new ModbusCrcException(frame));
         return;
       }
 

modbus/src/main/java/com/digitalpetri/modbus/exceptions/ModbusCrcException.java

@@ -0,0 +1,28 @@
+package com.digitalpetri.modbus.exceptions;
+
+import com.digitalpetri.modbus.ModbusRtuFrame;
+import java.io.Serial;
+
+public class ModbusCrcException extends ModbusException {
+
+  @Serial
+  private static final long serialVersionUID = -5350159787088895451L;
+
+  private final ModbusRtuFrame frame;
+
+  public ModbusCrcException(ModbusRtuFrame frame) {
+    super("CRC mismatch");
+
+    this.frame = frame;
+  }
+
+  /**
+   * Get the frame that caused the exception.
+   *
+   * @return the frame that caused the exception.
+   */
+  public ModbusRtuFrame getFrame() {
+    return frame;
+  }
+
+}