3 files changed, 28 insertions, 6 deletions
diff --git a/globals.c b/globals.c
index d63aa2e..90bfb39 100644
--- a/globals.c
+++ b/globals.c
@@ -13,7 +13,9 @@ GlobalStruct globals = {
 	.Registers.last_relay_driver_settings[1] = -1,
 	.Registers.last_relay_driver_settings[2] = -1,
 
-	.Registers.gpib_buffer[0] = 0
+	.Registers.gpib_buffer[0] = 0,
+
+	.4882Locks.locked_network_server = NO_SERVER_LOCKED
 };
 
 
diff --git a/globals.h b/globals.h
index a4b0745..52a3503 100644
--- a/globals.h
+++ b/globals.h
@@ -779,6 +779,12 @@ typedef struct {
 } HWDetectStruct;
 
 
+#define NO_SERVER_LOCKED -1
+typedef struct {
+	int command_in_progress;
+	int locked_network_server;
+} LockStruct;
+
 typedef struct {
 	ConstraintsStruct Constraints;
 	ChannelStruct ChannelState[max_channels];
@@ -793,6 +799,7 @@ typedef struct {
 	MenuStatusStruct MenuStatus;
 	RemoteStruct Remote;
 	HWDetectStruct HWDetect;
+	LockStruct 4882Locks;
 } GlobalStruct;
 
 
diff --git a/instr-daemon.c b/instr-daemon.c
index ec70f97..2097a6c 100644
--- a/instr-daemon.c
+++ b/instr-daemon.c
@@ -403,13 +403,26 @@ static gboolean periodic_poll (void)
 
 		Update_Main_Menu_If_Visible();
 
-		GPIB_check_for_device_clear_signal();
-		if (GPIB_check_for_messages(globals.Registers.gpib_buffer)) {
-			if (GPIB_handle_new_input(globals.Registers.gpib_buffer)) {
-				Parser_main(globals.Registers.gpib_buffer, 0, GPIB_send_query_response, NULL);
+		// don't check GPIB interface if a VXI interface is locked,
+		// or is currently handling a command
+
+		if ((globals.4882Locks.locked_network_server == NO_SERVER_LOCKED) &&
+		    (globals.4882Locks.command_in_progress == FALSE)) {
+
+			// tell VXI servers that the 4882 subsystem is busy
+			globals.4882Locks.command_in_progress = TRUE;
+
+			GPIB_check_for_device_clear_signal();
+			if (GPIB_check_for_messages(globals.Registers.gpib_buffer)) {
+				if (GPIB_handle_new_input(globals.Registers.gpib_buffer)) {
+					Parser_main(globals.Registers.gpib_buffer, 0, GPIB_send_query_response, NULL);
+				}
 			}
+			GPIB_check_for_device_clear_signal();
+
+			// tell VXI servers that the 4882 subsystem is avilable again
+			globals.4882Locks.command_in_progress = FALSE;
 		}
-		GPIB_check_for_device_clear_signal();
 
 		Update_Main_Menu_If_Visible();
 	}