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ANUAL
FT9Y-B1378
11-13
11: M
ODBUS
C
OMMUNICATION
Function Code 03 (Read Holding Registers) and Function Code 04 (Read Input Registers)
Function code 03 reads word device data of D (data register), T (timer preset value), or C (counter preset value). One through 64
consecutive words can be read out.
Function code 04 reads word device data of T (timer current value) or C (counter current value). One through 64 consecutive
words can be read out.
Communication Frame
Request from Modbus Master
ACK Reply from Modbus Slave
NAK Reply from Modbus Slave
Communication Example
RTU Mode
Purpose
Read 2 words starting at data register D1710.
D1710
(1710 – 0) + 400001 = 401711
Modbus address: 401711
Extract lower 5 digits
1711
1711 – 1 = 1710 = 6AEh
Communication frame address: 06AEh
Condition
Slave No. 8
D1710 data: 1234h
D1711 data: 5678h
Request from Modbus Master
08 03 06AE 0002 (CRC)
ACK Reply from Modbus Slave
08 03 04 12 34 56 78 (CRC)
NAK Reply from Modbus Slave
08 83 xx (CRC)
Slave No.
Function Code
Address
No. of Words
xxh
03h / 04h
xxxxh
xxxxh
Slave No.
Function Code
Quantity of Data
First High Byte
First Low Byte
Last Low Byte
xxh
03h / 04h
xxh
xxh
xxh
xxh
Slave No.
Function Code
Error Code
xxh
83h / 84h
xxh
Содержание SmartAXIS FT9Z-1A01
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Страница 10: ...TABLE OF CONTENTS Preface 9 SMARTAXIS PRO LITE USER S MANUAL FT9Y B1378...
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