For some purposes I looked back the data of some channels which don't exist any more. Here I explain how to do it.
If this method is not listed on the wiki, I will put this instruction on a wiki page.
(1) Edit an "ini" file which is not associated to the real-time control (e.g. IOP_SLOW.ini)
(2) In the file, write a channel name which you are interested in. The channel name should be bracketed like the other existing channels.
(3) Define the data rate. If you want to look at the full data, write
datarate = 2048
just blow each channel name.
Or if you want to look at only the trends, don't write anything.
(4) Save the ini file and restart fb. If necessary hit "DAQ Reload" button on a C1:AAA_GDS_TP.adl screen to make the indicators green.
(5) Now you should be able to look at the data for example by dataviewer.
(6) After you finish the job, don't forget to clean up the sentences that you put in the ini file because it will always show up on the channel list on dtt and is just confusing.
Also don't forget to restart fb to reflect the change.