Omega FMA 4000 User Manual page 31

Note: Address 00 is reserved for global addressing. Do not assign, the
global address for any device. When command with global address is
sent, all devices on the RS485 bus execute the command but do not
reply with an acknowledge message.
The global address can be used to change RS485 address for a particular device with
unknown address:
1. Make sure only one device (which address must be changed) is connected to the
RS485 network.
2. Type the memory write command with global address: !00,MW,7,XX[CR] where
XX, the new hexadecimal address, can be [01 – FF].
After assigning the new address, a device will accept commands with the new address.
Note: Do not assign the same RS485 address for two or more
devices on the same RS485 bus. If two or more devices with the same
address are connected to the one RS485 network, a communication
collision will take place on the bus and communication errors will occur.
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