Lika EM58 MB, User Manual

Page: 86 / 92

ES58 • EM58 MODBUS®
8.2 Using the 04 Read Input Register function code
EXAMPLE 1
Request to read the
Current position [0001-0002 hex]
parameter (registers 2
and 3) to the Slave having the node address 1.
Request PDU
(in hexadecimal notation)
[01][04][00][01][00][02][20][0B]
where:
[01] = Slave address
[04] =
04 Read Input Register
function code
[00][01] = starting address (
Current position [0001-0002 hex]
parameter,
register 2)
[00][02] = number of requested registers
[20][0B] = CRC
Response PDU
(in hexadecimal notation)
[01][04][04][00][00][2F][F0][E7][F0]
where:
[01] = Slave address
[04] =
04 Read Input Register
function code
[04] = number of bytes (2 bytes for each register)
[00][00] = value of register 2
Current position [0001-0002 hex]
, 00 00 hex =
0 dec
[2F][F0] = value of register 3
Current position [0001-0002 hex]
, 2F F0 hex =
12272 dec
[E7][F0] = CRC
Current position [0001-0002 hex] parameter (registers 2 and 3) contains the
value 00 00 2F F0 hex, i.e. 12,272 in decimal notation.
MAN ESx58x_EMx58x MB E 1.3 Programming examples 86 of 92