readtable seems to work well on this file.
t = readtable('Test Data.txt');
Warning: Column headers from the file were modified to make them valid MATLAB identifiers before creating variable names for the table. The original column headers are saved in the VariableDescriptions property.
Set 'VariableNamingRule' to 'preserve' to use the original column headers as table variable names.
Set 'VariableNamingRule' to 'preserve' to use the original column headers as table variable names.
head(t) % check the first 10 rows -> looks ok
         Date           Time      LineNumber    SystemStatus    Wav1_1    Wav1_2    Wav1_3    Wav1_4    Wav1_5    Wav1_6    Wav1_7    Wav1_8    Wav1_9    Wav1_10    Wav1_11    Wav1_12    Pow1_1    Pow1_2    Pow1_3    Pow1_4    Pow1_5    Pow1_6    Pow1_7    Pow1_8    Pow1_9    Pow1_10    Pow1_11    Pow1_12
    ______________    ________    __________    ____________    ______    ______    ______    ______    ______    ______    ______    ______    ______    _______    _______    _______    ______    ______    ______    ______    ______    ______    ______    ______    ______    _______    _______    _______
    {'2023/07/25'}    13:30:05      17892       {'0 0 0 0'}     1522.2    1526.2    1530.2    1534.2    1537.1    1542.2    1546.1    1550.2    1554.1    1558.1     1561.4     1566.1      29.1      29.2        29      28.4      35.6      36.9      38.1      42.3      41.4      43.6         38       39.8  
    {'2023/07/25'}    13:30:06      17893       {'0 0 0 0'}     1522.2    1526.2    1530.2    1534.2    1537.1    1542.2    1546.1    1550.2    1554.1    1558.1     1561.4     1566.1      29.1      29.3      29.1      28.3      35.6      36.9        38      42.3      41.4      43.5         38       39.8  
    {'2023/07/25'}    13:30:07      17894       {'0 0 0 0'}     1522.2    1526.2    1530.2    1534.2    1537.1    1542.2    1546.1    1550.2    1554.1    1558.1     1561.4     1566.1      29.1      29.2      29.1      28.4      35.6      36.8        38      42.4      41.4      43.5         38       39.7  
    {'2023/07/25'}    13:30:08      17895       {'0 0 0 0'}     1522.2    1526.2    1530.2    1534.2    1537.1    1542.2    1546.1    1550.2    1554.1    1558.1     1561.4     1566.1      29.1      29.3      29.1      28.4      35.6      36.8        38      42.4      41.4      43.6         38       39.7  
    {'2023/07/25'}    13:30:09      17896       {'0 0 0 0'}     1522.2    1526.2    1530.2    1534.2    1537.1    1542.2    1546.1    1550.2    1554.1    1558.1     1561.4     1566.1      29.1      29.3      29.1      28.4      35.6      36.8      38.1      42.4      41.4      43.6         38       39.8  
    {'2023/07/25'}    13:30:10      17897       {'0 0 0 0'}     1522.2    1526.2    1530.2    1534.2    1537.1    1542.2    1546.1    1550.2    1554.1    1558.1     1561.4     1566.1      29.1      29.3      29.1      28.4      35.7      36.9      38.1      42.4      41.4      43.4         38       39.7  
    {'2023/07/25'}    13:30:11      17898       {'0 0 0 0'}     1522.2    1526.2    1530.2    1534.2    1537.1    1542.2    1546.1    1550.2    1554.1    1558.1     1561.4     1566.1      29.1      29.2      29.1      28.3      35.6      36.9      38.1      42.2      41.4      43.5       37.9       39.7  
    {'2023/07/25'}    13:30:12      17899       {'0 0 0 0'}     1522.2    1526.2    1530.2    1534.2    1537.1    1542.2    1546.1    1550.2    1554.1    1558.1     1561.4     1566.1      29.1      29.3      29.1      28.4      35.6      36.8      38.1      42.3      41.4      43.6       38.1       39.7  
% access Wav1-1 column:
t.Wav1_1
ans = 598×1
1.0e+03 *
    1.5222
    1.5222
    1.5222
    1.5222
    1.5222
    1.5222
    1.5222
    1.5222
    1.5222
    1.5222
% access Wav1-2 column:
t.Wav1_2
ans = 598×1
1.0e+03 *
    1.5262
    1.5262
    1.5262
    1.5262
    1.5262
    1.5262
    1.5262
    1.5262
    1.5262
    1.5262
