Modbus gateways convert serial Modbus, also called Modbus RTU, to Modbus TCP. There is often confusion about which device type, vendor, and family to select when discovering one of these devices in EcoStruxure IT Gateway. You should always select the device you wish to monitor, most often a power or cooling device, but you might also want to monitor the Modbus gateway itself.
For basics on discovering devices in the EcoStruxure IT Gateway, see Discover Devices.
Discover Modbus TCP devices
Devices that can communicate using Modbus TCP are connected directly to the ethernet network without using a Modbus gateway. To discover Modbus TCP devices, you must select the appropriate device type, vendor, and family in the Gateway UI. This is the most common situation.
For example, to monitor an ION9000 Power Meter, discover it with Modbus TCP, select Power Meter, PowerLogic, and ION9000, enter its IP address, and, most often, the Modbus server address of 1 since that is typically the default address of devices that support Modbus TCP.
Discover serial Modbus devices connected to a Modbus gateway
Devices that are not capable of Modbus TCP and use only serial Modbus are often connected to a device that converts Modbus RTU to Modbus TCP, such as a Schneider Electric EGX or Com'X. To discover these devices, you use the TCP option on the EcoStruxure IT Gateway > Discover Devices page, and select Power Meter, PowerLogic, ION9000, and the IP address of the EGX/Com'X. Select the Modbus server address of your device, address 3 in this example.
You still use the ION9000 in this case even though the IT Gateway is connected to the Modbus serial to TCP converter because that device is just passing data through and is transparent to EcoStruxure IT Gateway.
To discover the branch circuit monitor, you need to run another discovery with Modbus server address 2, and then another discovery with Modbus server address 1 for the breaker.
Discover the Modbus gateway
Some devices, for example the Com’X 510, have digital and analog inputs. To monitor the status of those inputs, you need to monitor the Modbus gateway device. To discover these devices, you use the TCP option on the EcoStruxure IT Gateway > Discover Devices page, and select the vendor, device type, and family that matches the device. Consult the user manual for the device to determine the proper Modbus server address, 255 for the Com'X 510 in this example.
You can also monitor the power meter, branch circuit monitor, and breaker in addition to the Com'X. This requires four different discoveries, all with the IP address of the Com'X, and the appropriate Modbus server address for each: server address 255 for the Com'X; address 1 for the breaker; address 2 for the branch circuit monitor; and address 3 for the power meter.