Autonics SPR3 Series - Modbus RTU: Read Input Registers (Func 04-04 H)

1 Modbus RTU Protocol
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1.4 Read input registers (Func 04–04H)
Read the Binary data of Input Registers (3X reference) in Slave device.
(1) Query (Master)
Slave address Function
Starting address
No. of points
Error check (CRC16)
High
Low
High
Low
Low
High
1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte
(2) Response (Slave)
Slave address Function Byte count
Data Data Data Error check (CRC16)
High
Low
High
Low
High
Low
Low
High
1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte
If read the 2 values within the range from Input Register 300001 (0000 H) to 300002 (0001 H) on
Slave (Address 17) from Master.
 Query (Master)
Slave address Function
Starting address
No. of points
Error check (CRC16)
High
Low
High
Low
Low
High
11 H 04 H 00 H 00 H 00 H 02 H ## H ## H
If the values of 300001 (0000 H) and 300002 (0001 H) on Slave are respectively “10 (A H)” and
“20 (14 H)”.
 Response (Slave)
Slave address Function Byte count
Data Data Error check (CRC16)
High
Low
High
Low
Low
High
11 H 04 H 04 H 00 H 0A H 00 H 14 H ## H ## H
CRC16
CRC16