How does the System communicate with the software on PC?

The diagram below shows the full topology. Devices are grouped by how they communicate (Ethernet in blue, serial in green), and both branches converge on the PC at the right.

 The Ethernet path

The three Ethernet-driven modules — Robot, MiniHub, and Buret — plug into a 5-port Ethernet switch. The switch uplinks to a USB-to-Ethernet adapter, which plugs into the PC and presents as a single network interface. On the PC, each module is reachable by its own IP address over that one interface, so software can talk to all three independently. Four of the five switch ports are in use (three modules plus the uplink), leaving one spare port for future expansion.

The Serial path

The five serial devices — the two peristaltic pumps, the metering pump, the meter, and the temperature probe — connect to a 7-port USB hub, which in turn connects to the PC with a single USB cable. Each device enumerates as its own virtual COM port, so the PC addresses them individually even though they share one physical connection. Five of the seven hub ports are in use, leaving two spare.

Note: serial devices typically reach the hub through a USB-to-serial converter (or a built-in USB-serial interface on the device). Whichever is used, the hub sees each device as a USB endpoint and the PC sees it as a COM port.

What to expect at the PC

From the operator's point of view, the entire system reduces to two cables and two kinds of address:

• Two physical cables enter the PC — one USB cable from the hub and one USB cable from the network adapter.
• Ethernet modules are addressed by IP address on a single network interface.
• Serial devices are addressed as individual COM ports on a single USB connection.
• Spare capacity is built in: one free Ethernet switch port and two free USB hub ports.