E850-DTU(4440-GPRS) datasheet
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，成都亿佰特电子科技有限公司
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4. Function
4.1 Working mode
The working mode is master mode and slave mode, configured by Modbus register 40081
(0x0050). When the register value is 0, it is in master mode; when the register value is 1, it is slave
mode, the default slave mode.
4.1.1 Slave mode
In slave mode (register value 0x01), the data sent to the device by the network or 485 bus (sender)
conforms to Modbus RTU, Modbus TCP protocol, and the address in the data is the device address,
and the device will reply with the same protocol. If the data sent by the network or 485 bus to the
device does not comply with the Modbus RTU, Modbus TCP protocol, or even if the Modbus RTU and
Modbus TCP protocols are met, but the data address is not the device address, the data will be
discarded.
In the slave mode, the device can directly connect to the device in the master mode through the
485 bus. When the slave is not connected to the network, the network can also access the data of the
slave through the master.
