Reading More Than One Float Data Via ModBus RTU Using S7-1200 with CM1241


Thread Starter


Dear all

I want to use S7-1200 as Modbus RTU/Slave. When I want to read more float data from a salve and save to DB, I only received 0 value although i change value from slave.


Please help me resolve this problem
I'm not a Siemens guy but I saw this post and bookmarked it. Check out the last post in this thread at the link below regarding pointers for arrays.

I believe that the function block you show is a Modbus Master function block.

I can tell you that fetching as series of integers and thinking that you'll 'see' or 'read' floating point values will be a disappointment. IEEE 32 bit Floating point is not the same as 32 bit double integers.

Siemens must have some means of fetching double register, 32 bit floating point values and getting the correct interpretation, even if I don't know how to do it.