Communication with the Modbus/TCP stations is performed via a communications processor (CP) or via the integrated PN interface of the SIMATIC S7 CPU.

A SIMATIC S7 Controller can communicate with more than one Modbus/TCP station simultaneously, depending on the number of connection resources of the S7 CPU.

SIMATIC Modbus/TCP CP and Redundant V2 support the following CPs of the SIMATIC S7:

• S7 300
  • CP 343-1
• S7 400
  • CP 443-1

Use is possible only on CPs that support the function AG_CNTRL.

SIMATIC Modbus/TCP PN CPU, SIMATIC Modbus/TCP PN Red and SIMATIC Modbus/TCP SENTRON PAC support the following CPUs of the SIMATIC S7:

• ET 200
  • IM 151-8 PN/DP CPU
  • IM 154-8 PN/DP CPU
• S7 300/400
  • CPU 314C-2 PN/DP
  • CPU 315-2 PN/DP
  • CPU 317-2 PN/DP
  • CPU 319-3 PN/DP
  • CPU 412-2 PN
  • CPU 414-3 PN/DP
  • CPU 416-3 PN/DP
• S7-400 H (SIMATIC Modbus/TCP PN CPU and SIMATIC Modbus/TCP PN Red only)
  • CPU 412-5H
  • CPU 414-5H
  • CPU 416-5H
  • CPU 417-5H
  • CPU 410-5H
• Soft PLC (SIMATIC Modbus/TCP PN CPU only)
  • SIMATIC WinAC RTX
• SENTRON PAC (for SIMATIC Modbus/TCP SENTRON PAC)
  • PAC 3200, as of FW V2.2.1
  • PAC 4200, as of FW V1.5.1

The Modbus/TCP products have been released for standard CPUs, for F-CPUs, and for (PN)‑(H) CPUs.