PLCs: Modbus RTU on ABB AC250

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Re: PLCs: Modbus RTU on ABB AC250
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While there are variations I have never seen something as you describe. Here are two write examples.

1. Function Code 6, Preset Single Register:
   03 06 00 09 30 39 8C 38
Slave address 0x03, function code 0x06, register 0x0009 the value Decimal 12345 = 0x3039 CRC 0x8c38.

2. Function code 16 write multiple registers:
   03 10 00 09 00 02 04 04 D2 16 2E 17 08
Slave address 0x03, function code 0x10, registers 0x0009 for 0x0002 registers, 0x04 data bytes. Data is 1234=0x04d2 and 5678=0x162e. CRC 0x1708

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