I have trying to create an array of gpib instructions.

[Tbone]

The following is an example.

Time           instruction               X                  Y              Z

0 00:00:00,mot,v1_m1,-1492316.6919,-5204326.7860,3360431.4341,0,0,0,0,0,0,0,0,0,0,0

The problem is I can create the time format column array but putting in the string command instruction in the second column is giving me problems.

[Dennis_Knutson]

With an array, you cannot mix data types. Instead of a 2D numeric array, create a 1D cluster array. A cluster can have elements of different data types.