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Sending control characters via telnet

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I am using LabVIEW Full 6.0.2 in Windows (98 & 2000). I am trying to connect to a Linux system via TCP and have it send an email. I have an example that calls Excel to call Hyperterminal and uese it to connect and send the email. When I open a connection in Hyperterminal I get a return of "clogin: ". Using TCP Read after a TCP Open returns garbage. Any idea what I'm doing wrong or what I should look at next? I'm new to TCP in LabVIEW.

Also, how do I send a CTRL-d ?


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It sounds like you are trying to connect to the Linux system via telnet. LabVIEW by itself does not directly support the telnet protocol. You can use PuTTY as a client and call it from LabVIEW. There is a KB article on it here:


You can also purchase the Internet Connectivity Toolkit. It includes VIs specifically for the telnet protocol. The current shipping version will only work with LabVIEW 7.0 or higher, so you will need to udgrade as well if you choose that route. Of course if you upgrade, you will get the SMTP VIs that will allow you to connect to an SMTP server and send an email directly from LabVIEW. They were added in 7.0. There is a catch with using them and that is that they do not support SMTP authentication. If the SMTP server you are sending the email through requires a login before sending then they will not work. Also, they do not come with the Base package, so you will need Full or Pro.

The TCP VIs are pretty low level. You can read and write to a port, but the protocol that is being used on that port is not taken care of for you, be it telnet, ftp, smtp, http, or whatever. You can write the code to handle sending and receiving data for a particular protocol, but that is a lot of extra work. They are really designed for creating custom client/server applications.

John Ridpath

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