S        This expression returns the string at the specified position in the received binary message.

It takes one parameter, the 0-based byte index in the binary message to start reading from.


The binary message will be read until a null terminator character is found in the binary message (byte value 0).

In case of any error, the expression will return blank. The expression will also read blank if the character at the reading address is a null terminator.


In Blue Client, the Unicode text is tested for validity while reading to some extent; if it contains unreadable Unicode, the expression will fail with an error. However, the content can be undisplayable even if it's valid; examples include the zero-width space and other Format, Other category Unicode code points.

If you need a more complete test or limitation of content using a Unicode allowlist, you should do the checks on the server side, but there is a Convert string to UTF-8 and check against Unicode allowlist expression on the Client.


The text sent will be ANSI only in Lacewing Relay, so non-ANSI characters may be corrupted. More details on that here.