Hello,

no, you need to use same blocks as with S7-300/400 systems - P_SEND_RK and P_RCV_RK. I recommend in this case check documentation to CP341 module where all is described. One important attention, you need also blue dongle depended to selected role of CP341 as RTU protocol - Master or Slave. Without this specific dongle inserted to back side slot of CP341 you can't use blocks for communication.

On other side, there is some 3-rd party free driver from our user Tibi68 so you can try find his Topic and try set his blocks as user driver. In this case, dongle isn't required but only his special blocks. also support is closed from him probably but many posts in his Topic can be helpful.

Hello,

sry, now I discovered your LINK where documentation and TIAv15 prj is described.

But there you have clear informations what I've also described, use of blocks with CP341 and also on ET200S with 1SI MB RTU CM module. Check my attachment. Name of block you've mentioned is looks like some user defined block inside TIA example project what makes better handling of RK blocks probably. It isn't standard required FB block what is required to use, as other system comm blocks, it's up to programmer what code prepare for his better code functionality. Really I don't know, I don't have TIA v15 so pls open that TIA project and check inside, I expect this only simple helpful functionality. This change nothing to fact that it is required to use RK blocks with CP341, to my opinion.

Update:

Yes, it looks like as I said, here it is clear:

What is more strange is lack of important information about requirement use of Dongle module inside CP341 for functionality. I have no rpoblem with reading of  German language documents but I've not found any information inside documentation, what is big problem.