Settings for TCP Communication

If you have chosen the setting TCP in the Channel field, the TCP Communication tab is ready for input:

Field	Description
Host	Specifies the host name of the Modbus server. This might be, for example, one SPS. Note This entry is only required if you have set `Modbus Client` as the Modbus type.
Port	Specifies the TCP port. The standard port for the Modbus protocol is `502`.
Messages in Process	Specifies the maximum number of pending messages. These are messages that have not yet been processed by the connected server device. You can enter the maximum permitted number of messages here. This always makes sense if communication can also be asynchronous when TCP is used. In asynchronous communication, the Modbus agent does not wait for the response to the last message, but rather already sends the next message. If you enter a higher number of messages here, you can improve performance.
Modbus Client IPs	Specifies the list of permitted client systems. You can add as many IP addresses of devices here as you want. This is only possible if you have set PCo as the Modbus server. Since the Modbus protocol does not offer any direct security measures, the list of permitted clients is the only way of guaranteeing security.