I have a neslab chiller and want to read the temperature by sending ASCII characters and graph the results, any advice?

[Thriller]

I am having difficulty having the chiller recognize (RT[CR]) which is the signal recognized by the chiller to read the temperature. The signal that is returned is (xxx.xx[CR]) which is the temperature. I am attempting to be able to read the temperature and graph this vs time and possibly be able to change the setpoint as well from the UIR.

[Randy Solomonson]

It sounds like you are doing serial communication to a device. It may help to use hyperterminal for the initial stages.

First, use a paperclip to connect pins 2 and 3. Everything you type when 2 & 3 are connected should appear in hyperterminal. Then, if you remove the paperclip, nothing you type should appear in hyperterminal.

Then, connect the cable to the device. Type the commands in hyperterminal and see if you get a response. If you don't, you may not have a null modem cable, or you are not terminating the command with a proper termination character.

[RobertoBozzolo]

I agree with Randy that Hyperterminal is a good starting point to test cabling and communication.
In your program, be careful to serial port initialization (how to set baud rate, parity, data bits and stop bits depends on the language used) and to termination character ([CR] means Carriage return: if you are usng CVI it DOESN'T add CR to the message unless you esplicitly put it in).
Another interesting point is the time the instrument takes to respond to the message: it can vary from message to message and is usually described in the instrument's documentation. If you test for a shorter time, you catch a false 'no response'. You could make a while loop and test in it the number of bytes received, then decide whether to end the loop for timeout or answer recei
ved...
To continue help you, we need some details of your developing environment (CVI or LabVIEW?) and of problems you are having at present.
Hope to hear you soon
Roberto