User manual

IEC61131 User and Reference Manual
April 22, 2008
334
rxstring
Receive a Message String
Description
This function receives a message string on the specified communications port of a controller.
rxstring
enabl
comX
lenRe
done
strin
Arguments
Inputs
Type
Description
enable
Boolean
Set to TRUE to receive the string.
While this input is on and the complete message has
not yet been received, characters will continue to be
received and appended to the output string.
Enable must then be set to FALSE and back to TRUE
to receive another message.
comX
Integer
Communications Port.
Allowed values are 1-4
lenRequest
Integer
The number of characters to receive.
If lenRequest characters have been received, these
characters are copied to the output string, and the
done output is set to TRUE.
Any remaining characters will be left in the
communication port receive buffer, and may be read
in a subsequent call to this function.
Outputs
Type
Description
done
Boolean
Set to TRUE if the string of lenRequest characters
was successfully received.
Set to FALSE if the string was not received. This will
occur if there are less than lenRequest characters in
the buffer for comX, or if comX represents an invalid
communications port.
Set to FALSE if the comX port does not have Rx Flow
set to none and Protocol set to none.
string
Message
The returned message string.
Notes
The protocol must be set to „None‟ and the Rx Flow must be set to „None‟ for any
communication ports that use this function.