diff --git a/LuaLibs/RunMachParamFromSWCalc.lua b/LuaLibs/RunMachParamFromSWCalc.lua
index ff8528c..bb45f9a 100644
--- a/LuaLibs/RunMachParamFromSWCalc.lua
+++ b/LuaLibs/RunMachParamFromSWCalc.lua
@@ -143,10 +143,10 @@ function RunMachParamFromSWCalc.Exec()
          local dLayerTime = dTTrg
          if dLayerFeed == 0 then
             dLayerFeed = dFTrg
-            dLayerWait = dTMin - dLayerTime
          else
             dLayerTime = dTotLayerLength / dLayerFeed * 60
          end
+         dLayerWait = floor( dTMin + 0.5) - floor( dLayerTime + 0.5)
          -- calcolo la portata
          local Vf = dLayerFeed * ( ( dStrand - dSliceStep) * dSliceStep + pi * pow( dSliceStep / 2, 2)) / 1000
          -- calcolo speed
@@ -164,6 +164,7 @@ function RunMachParamFromSWCalc.Exec()
          if not bSpeedOk then
             dLayerFeed = ( MATERIAL.C1 * pow( ( dSpeed / ( MATERIAL.K / 100.0)), MATERIAL.C2)) * 1000 / ( ( dStrand - dSliceStep) * dSliceStep + pi * pow( dSliceStep / 2, 2))
             dLayerTime = dTotLayerLength / dLayerFeed * 60
+            dLayerWait = floor( dTMin + 0.5) - floor( dLayerTime + 0.5)
          end
          -- calcolo massa dello strato
          local dLayerMass = dTotLayerLength * dSliceStep * dStrand * MATERIAL.Density * 1e-6