7.2.2 About Connecting to Multiple Devices

For more details about communication methods (Direct Access Method and Memory Link Method), please refer to the following.
2.4 Device/PLC Communication

For example, Company A's driver (serial communication) is set to COM1 and Company B's driver is set to COM2 (serial communication).

A different driver can be designated for each COM port. However, each COM port can only have a single driver.
You can connect multiple devices with the same driver to each COM Port. However, the allowable number of devices/PLCs varies depending on the driver. Refer to the "GP-Pro EX Device/PLC Manual" for the allowable number of devices/PLCs.

For example, Company A's driver (serial communication) is set to COM1, and Company B, C, and D's drivers are set to the Ethernet port (Ethernet communication).

A maximum of four drivers can be used by the ports. However, one driver can be configured per COM port, and the remainder be used by the Ethernet port, or all 4 can be used by the Ethernet port and none by the COM ports. In the above example, COM1 has one driver set up (Company A's PLC), so the Ethernet port can handle three additional types of drivers (Company B, C, and D).
When using an Ethernet communication driver with multiple connections, [UDP] or [TCP] cannot be set up in the same driver.
For example, when [Device/PLC1] has been set to MELSEC A Ethernet [UDP] type, [Device/PLC2] cannot be set to MELSEC A Ethernet [TCP] type.

Connecting PLCs and Devices Without Communication Protocol (Direct Access Method + Memory Link Method)

Devices/PLCs and hosts (PCs, Microcomputer boards, etc.) can be connected at the same time.

For example, Company A's PLC is connected to COM1 by the direct access method, and the micro-computer board is connected to COM2 by the memory link method.

For addresses that can be used, refer to the following.
2.4.3 Using Direct Access and Memory Link at the Same Time

When multiple PLCs are connected to the display unit, the system data area can only have one PLC connected to it.

For example, In the following image, when four PLCs are connected to the display unit, only one of PLC1 to PLC4 can be set to the system data area.

For instruction on assigning System Data Area, refer to the following.
A.1.1.5 Device/PLC System Data Area Allocation Procedure
For details on addressing System Data Areas, refer to the following.
A.1.1.2 System Data Area (Direct Access Method)
A.1.2.2 System Data Area (Memory Link Method)
The System Data Area in the Direct Access Method (LS Area) and the System Data Area in the Memory Link Area are partially linked. For more details, refer to the following.
A.1.3.3 Restrictions When Using Direct Access and Memory Link Together