NEC Express 5800 User Manual page 266

Hardware
IMPORTANT:
 On the Network Menu, it is possible to change each digit of the
address from 000 to 256(decimal) effectively.
Examples)
1)Setting to 192
When 000 and select "Up" button twice, then it will become 200
When 200 and select "Down" button once,then it will become 190
When 190 and select "Up" button twice, then it will become 192
2)Setting to 168
When 000 and select "Up" button twice, then it will become 200
When 200 and select "Down" button 3 times,then it will become 170
When 170 and select "Down" button twice, then it will become 168
3)Setting to 255 or 000
When 000 and select "Down" button once, then it will become 255
When 255 and select "Up" button once,
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then it will become 000