How many socket connections does Modbus TCP/IP use to interface with other gateway / devices?

Issue

Does Modbus TCP/IP xDriver opens socket connection per each device or the gateway of the devices?

Product Line

Andover Continuum

Environment

NetController - CX9900, CX9940, CX9680, bCX9640.

BACnet Controller - bCX4040.

Cause

As some Modbus TCP/IP gateways have the limitation of maximum TCP/IP connections, if Modbus TCP/IP xDriver opens a socket per modbus device and keeps it open, the gateway might run into a problem due to the limited number of socket connections.

Resolution

The Modbus TCP/IP xDriver opens one(1) socket connection per server not device.

So for a gateway that has a number of devices, the Modbus TCP/IP xDriver only uses one(1) socket connection.