diff --git a/Console/Receiver/Spectrum Instrumentation m4i.4451/m4iset_extrig_rms.c b/Console/Receiver/Spectrum Instrumentation m4i.4451/m4iset_extrig_rms.c
index 93559b0c097f028b61fb0c99027ee7f8b9e93bb0..d90973792914842394a49347753edb2a18187ddd 100644
--- a/Console/Receiver/Spectrum Instrumentation m4i.4451/m4iset_extrig_rms.c	
+++ b/Console/Receiver/Spectrum Instrumentation m4i.4451/m4iset_extrig_rms.c	
@@ -5,11 +5,19 @@
 
 #include <stdio.h>
 
-
+/**
+ * Set m4i receiver card
+ *
+ * @param *pvData    16-bit data pointer for the received data
+ * @param *lMemsize  32-bit memory length for the received data
+ * @param *posttr    32-bit post trigger pointer to adjust the time window of the ADC. Please see manufacturer’s documentation for more about post trigger. 
+ * @Return void
+*/
 void m4iset_(int16 *pvData, int32 *lMemsize, int32 *posttr)
     {
-    drv_handle hDrv;
-    char szErrorText[ERRORTEXTLEN];
+    drv_handle hDrv;                    // Receiver device 
+    char szErrorText[ERRORTEXTLEN];    //  Error buffer
+    //Card specific parameters
     int32 lCardType;
     int32 allchan;
     int32 ausgabe;