Hello Luc, your points are well taken. I should rethink my approach as My serial port management is real complex, to share with you, it's a controlling two device circuits boards through two serial COM ports simultaneously. These device boards in turn needs to contol Weighbridges H/W like weighing scale, traffic lights, positioning beams etc. My confidence is getting better after discussing with you.:confused: Please stay tune. Very best Regards. Amarjeet.