From e2cb6aef729823ee5b98008c16a7d277fb4cd1a5 Mon Sep 17 00:00:00 2001
From: Michael Moon <triffid.hunter@gmail.com>
Date: Fri, 29 Apr 2011 10:08:58 +1000
Subject: [PATCH] M109 just waits if no temperature provided

---
 gcode_process.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gcode_process.c b/gcode_process.c
index f746271..45cb5dd 100644
--- a/gcode_process.c
+++ b/gcode_process.c
@@ -362,7 +362,8 @@ void process_gcode_command() {
 
 			// M109- set temp and wait
 			case 109:
-				temp_set(next_target.P, next_target.S);
+				if (next_target.seen_S)
+					temp_set(next_target.P, next_target.S);
 				if (next_target.S) {
 					power_on();
 					enable_heater();