Thanks it work perfectly.
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--  Machine up time
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local Milliseconds = mc.mcCntlGetPoundVar(inst, 3001 )
local seconds = string.format("%02.f", math.floor(Milliseconds/1000))
if seconds == 0 then
	scr.SetProperty("Machineuptime", "Label", "00:00:00")
else
	local hours = string.format("%02.f", math.floor(seconds/3600))
	local mins = string.format("%02.f", math.floor((seconds/60) - (hours*60)))
	local secs = string.format("%02.0f",(seconds - (hours*3600) - (mins*60)))
	scr.SetProperty("Machineuptime", "Label", hours ..":" ..mins ..":".. secs)
end