S7-1200 put/get

Hi, I have experienced a strange thing when using the GET function reading a S7-1200. Some of the tags I am trying to read from the remote PLC doesn’t work (no value in the receiving PLC), even if some of the tags in the same GET function is working. This goes for both M-tags and DBs. The ones that working are DBs, but with different address. Put/Get access for the PLC is on and the DBs does not have optimized block access. All DB properties looks the same for both the once that are working and the once that are not. Any ideas if there is any setting that I may have missed?

I done exactly the same with another S7-1200 PLC from the same supplier with the same programming structure without having this problem.

Do you have the box ticked to allow access to the processor?

With strange problems on the S7-1200 I often do a Factory reset and then reload the program. I have had strange issues when I have done an unkown number of online upgrades. Things almost as simple as 1 + 1 not equaling 2, I am there scratching my head, until I remember to do the reset.

How much data ?
On S7-1200 and S7-1500, PUT and GET have consistency only within 1 variable.
On S7-300, you can have consistency up to 32 Bytes.
Not sure why you have different results on different PLCs. There can be some randomness involved.

Can you use TSEND_C/TRCV_C instead of PUT/GET ?