diff --git a/src_main/io_devices/pican.cpp b/src_main/io_devices/pican.cpp
index 77a85eab..71f82417 100644
--- a/src_main/io_devices/pican.cpp
+++ b/src_main/io_devices/pican.cpp
@@ -91,7 +91,7 @@ int PICAN::readDevice(void * read_to, int max_size) {
 	//piCoutObj << "receive CAN frame Id =" << frame.can_id;
 	memcpy(read_to, frame.data, piMini(frame.can_dlc, max_size));
 	readed_id = frame.can_id;
-	return max_size;
+	return piMini(frame.can_dlc, max_size);
 #endif
 	return 0;
 }