Lika SMAX-AI1-PRG-L2, User Manual

Page: 78 / 84

SMAX MODBUS®
8.2 Using the 04 Read Input Register function code
EXAMPLE 1
Request to read the
Current position [0001 hex]
parameter (register 2) to the
Slave having the node address 1.
Request PDU
(in hexadecimal notation)
[01][04][00][01][00][01][60][0A]
where:
[01] = Slave address
[04] =
04 Read Input Register
function code
[00][01] = starting address (
Current position [0001 hex]
parameter, register 2)
[00][01] = number of requested registers
[60][0A] = CRC
Response PDU
(in hexadecimal notation)
[01][04][02][13][C5][74][53]
where:
[01] = Slave address
[04] =
04 Read Input Register function code
[02] = number of bytes (2 bytes for each register)
[13][C5] = value of register 2
Current position [0001 hex]
, 13 C5 hex = 5061
dec
[74][53] = CRC
Current position [0001 hex]
parameter (register 2) contains the value 13 C5
hex, i.e. 5061 in decimal notation.
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