diff --git a/src/sysVcom.php b/src/sysVcom.php
index c4e1c2d..8e6fd9b 100644
--- a/src/sysVcom.php
+++ b/src/sysVcom.php
@@ -16,6 +16,8 @@
  
 $g_procName = 'BU-commander';
 //posix_mkfifo( $g_procName, 0644 );
+$g_k_caller = null;
+$g_k_reply = null;
 
 //max msg length - this fails on Mint-21. Trial and error gives a max size of 8182.
 //$g_max_chan = file_get_contents('/proc/sys/kernel/msgmnb');
@@ -25,11 +27,35 @@
 // larger was not enough but 100 was emough. I mean, go figure ???
 $g_max_rcv = $g_max_chan+100;
 
-$g_max_data = $g_max_chan - 2;	//we use the first 2 bytes for msg chunks
-$g_k_caller = ftok( $g_procName, 'A');		//caller
-$g_k_reply = ftok( $g_procName, 'B');		//reply
+$g_max_data = $g_max_chan - 2;
 
 
+function rpc_setGlobals( $name, $value ){
+
+		
+	switch( $name ){
+	
+	case 'procName':
+		global $g_procName;
+		global $g_k_caller;
+		global $g_k_reply;
+		$g_procName = $value;
+		$g_k_caller = ftok( $g_procName, 'A');		//caller
+		$g_k_reply = ftok( $g_procName, 'B');		//reply
+		break;
+	
+	case 'max_chan':
+		global $g_max_chan;
+		global $g_max_rcv;
+		global $g_max_data;
+		$g_max_chan = $value;
+		$g_max_rcv = $g_max_chan+100;
+		$g_max_data = $g_max_chan - 2;	//we use the first 2 bytes for msg chunks
+		break;
+	}
+
+}
+
 //************************************************************************************************************************
 // The following functions all relate to making an RPC.
 // They use the php serialize() to send objects across the process boundary
@@ -41,6 +67,7 @@
 
 function rpc_listen( &$caller_id, &$msgArr, $bBlock = true ){
 	$caller_id = IPC_listen( $msgArr, $bBlock );
+	if($caller_id==0 && !$bBlock) return null;
 	return unserialize( $msgArr[$caller_id]['msg'] );
 }
 
@@ -55,15 +82,12 @@
 // of a function or parameters.
 //
 
-function clear_IPC( ){
-
-	global $g_k_caller;
-	global $g_k_reply;
-
-	$q_caller = msg_get_queue($g_k_caller);
+function clear_IPC( $g_procName ){	
+	
+	$q_caller = msg_get_queue( ftok( $g_procName, 'A') );
 	msg_remove_queue($q_caller);
 	
-	$q_reply = msg_get_queue($g_k_reply);
+	$q_reply = msg_get_queue( ftok( $g_procName, 'B') );
 	msg_remove_queue($q_reply);
 	
 }