Hi Carlos,
I think you'll need to set up an example - ideally with TPS (which also support blobs) for what you are trying to do.
Blobs are not the same as "big strings" and aren't typically used to hold "big string data", so they behave differently to string fields, both at the Clarion driver level, and the NetTalk level.
So take one of the shipping examples, tweak it a bit to contain a blob, and let's see what can be done.
cheers
Bruce