I've run into some issues running the probably obsolete Lakeshore DRC-91CA temperature controller in the lab and I'm hoping someone here has some Ideas on what's causing these problems. The temperature controller is currently hooked up to an old computer through an IEEE/GPIB cable and is controlled through this computer using a program I've written in pascal which is sequenced through MPMS-Multivu. The device seems to randomly decide when its going to accept commands and when it's not going to. I know from experience that it has never worked when you turn the temperature controller on after opening MPMS multivu and only sporadically when its turned on beforehand. I'm fairly sure that it's only an issue with the temperature controller and not with the other devices used. When you send a command the device returns an error "I/O Canceled". I know that if I send an incorrect command or a command with an invalid carriage return then the device will return an error "Invalid Command" and if the command is being sent to a device that doesn't exist I'll get "No Listener". I've read through the manual for the temperature but it was no help, if anyone has any experience with anything like this and would like to let me know what's going wrong and what I have to do to fix it, I'd really appreciate it.