Problem with integer variable and vector range

FvM already gave you an alternative solution.

One other solution would be:

if (OutputNumber == "000000") then

MyVector(37 downto (38-0)) <= Temp(37 downto (38-0)); <- This is wrong because your code was wrong

end

if (OutputNumber == "000001") then

MyVector(37 downto (38-1)) <= Temp(37 downto (38-1));

end

if (OutputNumber == "000010") then

MyVector(37 downto (38-2)) <= Temp(37 downto (38-2));

end

if (OutputNumber == "000011") then

MyVector(37 downto (38-3)) <= Temp(37 downto (38-3));

end

if (OutputNumber == "000100") then

MyVector(37 downto (38-4)) <= Temp(37 downto (38-4));

end

...

if (OutputNumber == "01010") then

MyVector(37 downto (38-10)) <= Temp(37 downto (38-10));

end

There is no need to use conv_integer. And pleas use numeric_std instead of standard_arith