Serial Connection with VFD using VISA Write and Read

[MarcusG1]

Hello,

I am attempting to control a Mitsubishi Electric D720 VFD with LabView 2015 using serial communication with an RS485 cable. I started with the simple serial example VI and expanded it from there. Right now I am having trouble with the read function. I get an output of 24 bytes from the write function, but I get a timeout error for the read function. I attached screenshots of the front panel and block diagram to this as well as the VI. If you have any advice or would like me to clarify anything, please let me know.

Thanks,

Marcus

[iBrent]

Does your device require an EOL character for the write? Such as line feed or carriage return? Append a \r to the end of the concatenate string and try again.

[MarcusG1]

Hi Brent,

A setting in the protocol allows the absence of an EOL character, so I was attempting to leave it out. However, I changed this setting and added the carriage return, but I am still getting the timeout error.

[iBrent]

are you able to communicate with the device using a terminal program? hyperterminal, putty, etc?

[MarcusG1]

Using Putty, I can open up a session window, so I think I am communicating with it. However, I cannot type anything in the window, so maybe there is a problem with that?

[iBrent]

Yup, there is a problem with that. Be able to talk to it first, then LabVIEW later. It'll be a lot easier to diagnose once you are sure you can talk to it. Check cables, protocol, baud rate/serial settings, etc. in putty. Then we can transfer that over to NI VISA.