UPS2000-(6 kVA-20 kVA)
Modbus Protocol Development Guide
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
Register address: Every signal or parameter of the slave devices corresponds to an address.
The host obtains the relevant information or sets the relevant parameters. These processes are
completed by accessing these register addresses.
Slave node address: this address is the RMS-MODBUS01A card address, set by the dual
in-line package (DIP) switch. The range is from 1 to 247.
1.3 Physical Interface
1.3.1 Serial Communication Electrical Standards
The slave nodes communicate with the master node through the RS485 or RS232 serial ports.
Information transmission method:
1. Use the RTU transmission mode of the Modbus.
2. The transmission mode for the character information is asynchronous mode using a
frame format of one start bit, eight data bits (information byte), and one stop bit. (10 bits
in total.)
1.3.2 Data Transmission Speed
The data transmission baud rate is fixed at 9600 bit/s.
When connecting to a network management system (NMS), use an RS485/232 converter with the
isolation function. A hot-swap RS485/232 converter is not recommended.
1.3.3 Cable Connection
Step 1 Set a hardware address for the Modbus card.
The hardware address is set over S2 (RS485 address DIP switch) shown in Figure 1-1. As
shown in Figure 1-2, the address contains eight digits. If a toggle switch is set to ON, it stands
for 0. If a toggle switch is set to OFF, it stands for 1.
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