To talk via Ethernet to a Siemens S7 PLC, you need the S7NT driver in Citect, together with either a Siemens CP1413, CP1613 card or a normal Ethernet card. You also need the S7 API from Siemens (S7-1413 or S7-1613 when you use a CP1413 or a CP1613 card). See Q3007 for more details.

Both the CP1413 and the CP1613 card allow you to run these two protocols (SINEC and S7NT) simultaneously. So you only need one Siemens card.

When you use the CP1413 card you only have to define a single 'Access point of the application' in the Siemens applet 'Setting the PG/PC interface'.

When you use the CP1613 card you need to have two 'Access points of the application' in the Siemens applet 'Setting the PG/PC interface, one that uses the TF functions (for the S5 connection), and one that uses the S7-functions (for the S7 connection). These two access points work similarly to network protocol bindings in Windows, and can be both used at the same time.

Note:

You cannot use a standard Ethernet card (like a 3COM card) to talk to a S5 PLC via the SINEC driver. Only way to talk to a S5 via a standard NIC is via the Siemens S7-OPC Server and Citect's OPC Client; however this only supports SEND/RECEIVE functions for the S5 (this is called S5-compatible communication in the Siemens documentation), so the TF-functions are not supported. To use this OPC server, you need also the Softnet-S7 software from Siemens.