The simplest way is to write your arduino code to send both values at once with a comma between them and terminated with a carriage return. The pntln function adds the termination character for you. No need to use the channel id. The Spreadsheet String to Array can be used to separate the values. The VISA Read would be configured to detect the termination character and stop automatically when it is detected. An arbitrary high number of bytes to read is specified so the read set-up is simplified.
If your existing scheme appends a CR, then you would need to read x number of bytes to get the channel, pass that data to a case statement, read y number of bytes to get the data, and then write to one of two arrays (or one array and the appropriate column).
Numerous discussions on this subject and the LINX toolkit is available to create the necessary sketch.
