@mkrupicka Hello Michal,
thank you for your post. You are right - the behaviour of PJSOCT function block is not as one would expect. However it is also caused by format of "id" item - since the value is written without quotation marks it represents number by the definition.
I would use different approach:
search the string for substring "id" offset the position (I presume that the message structure is given) extract substring (I presume that the ID length is given)cfc11698-ac5b-4527-bb9a-989303ca4380-image.png
If you need any help just let me know.
Kind regards,
Tomas