Hardware manual

Chapter2 Connection to a PLC
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FC16 Write multiple registers
Writing to Holding Register (HR) consecutively
(Request)
Byte 7 FC (Function code) = 10 (HEX)
Byte 8-9 Reference No.
Byte 10-11 Number of write words (1 to 100 words)
Byte 12 Number of write bytes (2 x number of write words)
From Byte 13 Write data
(Normal response)
Byte 7 FC (Function code) = 10(HEX)
Byte 8 Reference No.
From Byte 9 Number of write words
(Abnormal response)
Byte 7 FC (Function code) = 90 (HEX)
Byte 8 Exception code 01 or 02
(Example)
Writing to HR400001 (1 word). The write value is 1234 (HEX).
10 00 00 00 01 02 12 34 => 10 00 00 00 01