SIMATIC NET

this is a hard thing to answer only with these fewinformation’s but I will try.

I think the PLC’s you talk about are S7 PLC’s. The connection you talk about is, as far as I expect an Ethernet Connection. So I think if you have a Server you may have either a Standard NDIS Network card or the CP 1613.

In this Case I would think you should have

for the NDIS Card:
Softnet S7 Lean for Industrial Ethernet (6GK1704-1LW63-3AA0)

for the CP 1613 Card:
S7-1613 for Industrial Ethernet. (6GK1716-1CB63-3AA0)

I hope this could help you a bit.

Best regards