Siemens SIMATIC S7 Manual page 6

Additional
Questions
Terminology
Scope of
Application
MODBUS / TCP communication via the integrated PN interface of the CPU
2XV9450-1MB02; Manual edition 2.1
For further questions regarding the use of the FBs described in this manual,
please contact your Siemens partner who provided you with this function
block.
This document uses the term PN PLC. The descriptions apply to PN PLCs
of series 315, 317, 319, 414 and 416 as well as IM 151-8 PN/DP CPU.
The function block described in this manual establishes a connection
between a PN PLC and third-party MODBUS devices.
Preface
3