LR200EM interior design consists of “Ethernet to UART” and “UART to LoRa” (see below diagram)
For “Ethernet to UART”, one side is “Ethernet” as TCP, and the other side is “UART” as RTU.
Modbus type is to define the query command transmission direction between “Ethernet (TCP)” and “UART (RTU)”.

Below diagram illustrates PC Client sends query command to LR200EM (server).

The query command first reaches the “Ethernet” of the LR200EM (server) and enters the LR200EM (server), so the query command transmission direction in LR200EM (server) is from “Ethernet (TCP)” to “UART (RTU)”, so Modbus type of the LR200EM (server) should be defined as “TCP to RTU Slave”.

The query command will then be sent via LoRa from LR200EM (server) to LR200EM (client). After LR200EM (client) receives the query command, the query command transmission direction in LR200EM (client) is, it will be passed to “UART (RTU)” first, and then to “Ethernet (TCP)”. So Modbus type of the LR200EM (client) should be defined as “RTU to TCP Slave”. However it also works when defined as “TCP to RTU Slave”.