Hi, I have a cooler and a pressure gauge which I need to operate from Matlab. Both devices are connected to the computer via a serial port. I've been using the Matlab Instument Toolbox Test & Measurement tool to try and communicate with these machines. The problem is that I don't get any data from them, and as far as I know, can't send them any data either. The manual for the cooler can be found http://golem.merate.mi.astro.it/projects/rem/secure/archives/manuals/polar7/GA125004E.pdf" [Broken] and a description of the RS-232 interface in part 4 of that document. I've set up the baud speed, number of data bits and stop bits, parity and terminator as specified. But if I try to send any commands to the device, I get no reply before the timeout. I've sent the data in ASCII format and I've tried the different data formats, but I get no response. Can you tell me what is it that I'm doing wrong?