how to converts rs232 to parallel port
Thank you for your response
let me explain my situation more clear
My system consist of two pump,one 1.5HP and the other a small 5-10watt or 60-120watt.I decide to buy an inverter to control the main pump(although I dont buy this until know,what inverter do you recommended which brand,altivar11 or altivar31 from telemacanique,or vacon ,lg ,abb)all of these inverters had a4-20ma analog output.
the small pump is controlled by a potentiometer,as I say I want to remove these potentiometer and with the 4-20ma signal of the inverter controll the pump,first I think that it is possible to convert the 4-20ma to 0-5v i found some suitable circuits and commericial products and so there Is no need to buy a seperate plc.
Then I think that if i want to add several small pumps later what can i do and because the labview is simple and powerfull software and is easy to operate i can use it but its cards are very expensive and the only situation remained is to use serial ports or usb and parallel ports that can be controlled these cheap small pumps.
as i say i newbie in electronic so plz if possible send more infomation,how can i find characteristic of that potentiometer and information to simulate it with any manner,how can i buy those microcontroler that dear IanP mentioned and if i cant find them in my area how can replace them with a suitable one and after that which other electrical components i must buy. and what is the estimated price of these project.
Pardon me for my bad english and Thank You again for your response.
siyamak