diff --git a/Inc/SerialPortFrameIO.h b/Inc/SerialPortFrameIO.h
index 5cf33d8..828ad2e 100644
--- a/Inc/SerialPortFrameIO.h
+++ b/Inc/SerialPortFrameIO.h
@@ -7,13 +7,14 @@
 #include "stdint.h"
 
 typedef uint16_t (*SerialPortFrameIOTransaction  )(void *env, uint8_t *data, uint16_t size, uint32_t timeout);
+typedef uint16_t (*SerialPortFrameIOTransmitTransaction  )(void *env, uint8_t *data, uint16_t size, uint32_t adr,
+                                                   uint8_t canType, uint8_t mailBox, uint32_t timeout);
 
 typedef struct {
     void *env;
     SerialPortFrameIOTransaction receive0;
     SerialPortFrameIOTransaction receive1;
-    SerialPortFrameIOTransaction transmit;
-    SerialPortFrameIOTransaction transmit1;
+    SerialPortFrameIOTransmitTransaction transmit;
 } tSerialPortFrameIO;