Regarding your update. Character 255 is the Telnet IAC (Interpret as Command) escape character. Telnet commands are two byte sequences with the IAC as the first byte and the command character as the second byte. You may be able to get away with just doubling the IAC character whenever you want send it (\xff) as data. If that doesn't work, you'll probably need to not use Telnet and just set up your own raw TCP connections using IO::Socket or an equivalent.

In reply to Re: Telnet.pm and Negative Values for Modbus by thundergnat
in thread Telnet.pm and Negative Values for Modbus by PaulNg

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