优化

mes/hd/nladmin-system/src/main/java/org/nl/wms/ext/bigScreen/service/impl/DeviceScreenServiceImpl.java

@@ -40,6 +40,10 @@ public class DeviceScreenServiceImpl implements DeviceScreenService {
         //查询暂未生产设备
         int prepare_device = task_rows.size() - run_device;
 
+        if (prepare_device < 0) {
+            prepare_device = 0;
+        }
+
         //空闲设备
         int free_device = total_num - task_rows.size() - err_device;